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TC Ord. No. 2012-06 Approving a permit for areas and activities of state and local interest (1041 permit)TOWN OF AVON, COLORADO ORDINANCE 12 -06 SERIES OF 2012 AN ORDINANCE APPROVING A PERMIT FOR AREAS AND ACTIVITIES OF STATE AND LOCAL INTEREST (1041 PERMIT) FOR THE EAGLE RIVER WATER AND SANITATION DISTRICT FOR AN EXPANSION OF THE AVON WASTEWATER TREATMENT PLANT WHEREAS, the Town of Avon ( "Town ") is a home rule authority municipal corporation and body politic organized under the laws of the State of Colorado and possessing the maximum powers, authority and privileges to which it is entitled under Colorado law; and WHEREAS, Chapter 7.40 of the Avon Municipal Code authorizes the Town to review permit requests for areas and activities of state and local interest (1041 Permits); and WHEREAS, Eagle River Water and Sanitation District ( "the Owner ") has submitted an application for a 1041 Permit to expand the Avon Wastewater Treatment Plant; and WHEREAS, pursuant to Section 7.40.660, Approval of permit application, Avon Municipal Code, the Town Council has considered the applicable review criteria; and WHEREAS, the Town Council held public hearings on May 22, 2012 and June 12, 2012 after posting notice of such hearing in accordance with the requirements of Section 7.40.250, Public notice requirements, Avon Municipal Code, and considered all comments provided before taking action; and WHEREAS, it is the Town Council's opinion that the health, safety and welfare of the citizens of the Town of Avon would be enhanced and promoted by the adoption of this ordinance; and WHEREAS, approval of this Ordinance on first reading is intended only to confirm that the Town Council desires to comply with the requirements of the Avon Home Rule Charter by setting a public hearing in order to provide the public an opportunity to present testimony and evidence regarding the application and that approval of this Ordinance on first reading does not constitute a representation that the Town Council, or any member of the Town Council, supports, approves, rejects, or denies this ordinance; NOW THEREFORE, BE IT ORDAINED BY THE TOWN COUNCIL OF THE TOWN OF AVON, COLORADO, the following: Section 1 Recitals Incorporated The above and foregoing recitals are incorporated herein by reference and adopted as findings and determinations of the Town Council. Ord 12 -06 1041 Permit for Avon WWTP Expansion May 22, 2012 Second Reading revision Page 1 of 3 Section 2 Approval of a 1041 Permit The 1041 Permit for the expansion of the Avon Wastewater Treatment Plant as outlined in the Staff Memorandum dated May 22, 2012 and June 12, 2012 is hereby approved with the following conditions: 1. In addition to its use during peak seasonal periods as determined by the Eagle River Water and Sanitation District, the Chemically Enhanced Primary Clarification system will also be operated as a rapid response to odor incidents at the Avon Wastewater Treatment Plant. Section 3 Severability If any provision of this Ordinance, or the application of such provision to any person or circumstance, is for any reason held to be invalid, such invalidity shall not affect other provisions or applications of this Ordinance which can be given effect without the invalid provision or application, and to this end the provisions of this Ordinance are declared to be severable. The Town Council hereby declares that it would have passed this Ordinance and each provision thereof, even though any one of the provisions might be declared unconstitutional or invalid. As used in this Section, the term "provision" means and includes any part, division, subdivision, section, subsection, sentence, clause or phrase; the term "application" means and includes an application of an ordinance or any part thereof, whether considered or construed alone or together with another ordinance or ordinances, or part thereof, of the Town. Section 4 Effective Date This Ordinance shall take effect thirty days after final adoption in accordance with Section 6.4 of the Avon Home Rule Charter. Section 5 Safety Clause The Town Council hereby finds, determines and declares that this Ordinance is promulgated under the general police power of the Town of Avon, that it is promulgated for the health, safety and welfare of the public, and that this Ordinance is necessary for the preservation of health and safety and for the protection of public convenience and welfare. The Town Council further determines that the Ordinance bears a rational relation to the proper legislative object sought to be obtained. Section 6 No Existing Violation Affected Nothing in this Ordinance shall be construed to release, extinguish, alter, modify, or change in whole or in part any penalty, liability or right or affect any audit, suit, or proceeding pending in any court, or any rights acquired, or liability incurred, or any cause or causes of action acquired or existing which may have been incurred or obtained under any ordinance or provision hereby repealed or amended by this Ordinance. Any such ordinance or provision thereof so amended, repealed, or superseded by this Ordinance shall be treated and held as remaining in force for the purpose of sustaining any and all proper actions, suits, proceedings and prosecutions, for the enforcement of such penalty, liability, or right, and for the purpose of sustaining any judgment, decree or order which can or may be rendered, entered, or made in such actions, suits or proceedings, or prosecutions imposing, inflicting, or declaring such penalty or liability or enforcing such right, and shall be treated and held as remaining in force for the purpose of sustaining any and all proceedings, actions, hearings, and appeals pending before any court or administrative tribunal. Ord 12 -06 1041 Permit for Avon WWTP Expansion May 22, 2012 Second Reading revision Page 2 of 3 Section 7. Publication by Posting The Town Clerk is ordered to publish this Ordinance by posting notice of adoption of this Ordinance on final reading by title in at least three public places within the Town and posting at the office of the Town Clerk, which notice shall contain a statement that a copy of the ordinance in full is available for public inspection in the office of the Town Clerk during normal business hours. INTRODUCED, APPROVED, PASSED ON FIRST READING, ORDERED POSTED AND REFERRED TO PUBLIC HEARING and setting such public hearing for 5:30 on June 12, 2012 at the C ers of the Avon Municipal Building, located at One Lake Street, Avon, Colorad y * SEAL, Kristi 'Ferraro, Mayor Pro Tem Published by posting'HfWF three public places in Town and posting at the office of the Town Clerk at least seven days prior to final action by the Town Council. ATTEST: i Catherine Mythen, Deputy own Clerk INTRODUCED, ORDERED PUE IED BY POS7 :S EA E APPROVED S O ORM: Eric own Attorney AND PASSED ON SECOND READING, AND G on June 12, 2012. is arroll, Mayor Published by posting by title in at least three public places in Town and posting by title at the office of the Town Clerk. ATTEST: C-J" & qV1,A Catherine Mythen, Deput Town Clerk Ord 12 -06 1041 Permit for Avon WWTP Expansion May 22, 2012 Second Reading revision Page 3 of 3 To Honorable Mayor and Town Council From Jared Barnes, Planner I Thru Patty McKenny, Interim Town Manager Eric Heil, Heil, Town Attorney Date June 12, 2012 Meeting Re Second Reading: Ordinance No. 12 -06, Series 2012: An Ordinance Approving A Permit For Areas And Activities of State And Local Interest (1041 Permit) Avon Wastewater Treatment Plant Expansion — PUBLIC HARING Update: At the May 22, 2012 meeting, the Town Council discussed the proposed Avon Wastewater Treatment Plant expansion. Ultimately, the Council approved the first reading of Ordinance 12 -06 after discussion on the proposed project took place. The Council did express concern with the lack of referral sent to Northwest Colorado Council of Governments ( NWCOGG) Water Quality division, the Eagle River Watershed Council, and the Eagle County Environmental Health department. Staff has contacted these agencies and solicited feedback. Both NWCOGG Water Quality division and Eagle County Environmental Health department stated that they were aware of the proposed modifications to the plant and had signed off on the improvements as a part of the National Permit Discharge Effluent Standards (NPDES) and Colorado Discharge Permit System (CDPS) approval processes. Staff also discussed the proposed improvements with the Eagle River Watershed Council, who had no objections to the request. The Council also asked Staff to discuss the CEPC process with the other Wastewater Treatment Plants that have used or are currently using the process or Ferric Chloride. The Littleton - Englewood Wastewater Treatment Plant has used Ferric Chloride in the past, but currently uses Ferric Sulfide because they were noticing an increase in the metal content in their biosolids. The representative did state that Ferric Chloride would be considered in the future due to the ability to use a cleaner version than what was utilized in the past. Both the Metro Wastewater Reclamation District and Southgate Sanitation District have used this process successfully in the past. Neither District had any negative feedback from their use of the process. Summary: The Eagle River Water and Sanitation District (ERWSD) is proposing to expand the Avon Wastewater Treatment Plant (the Project). The Permit Application for Areas and Activities of State and Local Interest (1041 Permit) is submitted pursuant to the Town of Avon's 1041 Regulations ((Title 7, Chapter 7.40, Avon Development Code ( "ADC ")) which requires a permit for "major extensions of existing domestic water and sewage treatment systems ". This permit application requests approval to construct a Chemically Enhanced Primary Clarification (CEPC) Facility at the Avon Wastewater Treatment Plant (WWTP) and increase the Avon WWTP's organic capacity by twenty-five percent (25 %). The CEPC Facility will be located within the existing Avon WWTP's building footprint located at 950 W. Beaver Creek Blvd (the Property) which is zoned Public Facility (PF). Accompanying this memorandum is the complete Application, dated March, 2012 (Exhibit A). The Application document includes all of the submittal information required by the ADC, including but not limited to: executive summary; summary of alternatives; detailed plans and specifications; federal, state, and local permits and approvals; environmental impacts and mitigation; need for proposed project; and, technical and financial feasibility. Town Staff had concern over the lack of in -house expertise to review technical documents related to wastewater treatment facilities. Michael Lutz of Dewberry was chosen as a consultant to work with Staff and provide third -party review. A Memorandum dated May 9 2012 from Michael Lutz, Dewberry, summarizes their review and is attached as Exhibit B. The final attachment is Ordinance 12 -06 (Exhibit C) which would approve the Permit request with conditions and findings. Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 11 Process: Pre Application conference A pre - application conference with the Applicant to discuss the 1041 Regulations and the permit process was conducted on January 23, 2012. Application Submittal The application was determined to be complete on April 16, 2012, at which time all of the mandatory application copies were accepted by Staff. The submittal requirements are governed by, ADC Section 7.40.220, Application Submittal Requirements. Agency Referrals Outside agency referrals were solicited via e -mail with a link to the complete application on the Town's website ( www.avon.orglreferral ) on April 24, 2012. Agencies included in the referral were: Eagle County Planning Department, Eagle County School District, ECO Trails, Eagle River Fire Protection District, and Eagle County Health Service District. Staff has not received any comments from the referral agencies. Published Notice As required by ADC Section 7.40.250, Public Notice Requirements, a public notice was published, on April 22, 2012 in the Vail Daily newspaper, at least 30 days in advance of the Town Council public hearing. Public Hearing The formal permit hearing with Town Council is set for May 22, 2012. The Council shall either approve or deny the permit by acting on Ordinance 12 -06 at the hearing after all relevant testimony has been heard. Review Considerations: According to ADC Section 7.40.660, Approval of Permit Application, the Council shall consider the following: (a) All of the provisions of the 1041 Permit application procedure set forth in Article Ili of these Regulations have been complied with; (b) Demographic trends demonstrate a need for the Special Water and Wastewater Project (SWWP) in order to timely serve existing and future residents and businesses within the Town; (c) Desirable local and regional community land use patterns will not be disrupted due to the location of the proposed construction, expansion, or modification of the SWWP; (d) The construction, expansion or modification of all dams or other impoundment structures required by the SWWP, if any, will comply with engineering requirements specified by the Colorado Water Conservation Board and the Office of the State Engineer. (e) The proposed SWWP is not subject to significant risk from earthquakes, floods, fires, subsidence, expansive soils, avalanches, landslides, or other natural hazards. (f) The proposed SWWP will not present an unreasonable risk of exposure to toxic or hazardous substances within the impact area. (g) The proposed SWWP will not significantly deteriorate floodplains, wetlands or riparian areas in the impact area. (h) The proposed SWWP will not significantly degrade existing visual quality, noise and vibration levels, or odor levels in the impact area. (i) The proposed SWWP is technically and financially feasible. 0) The proposed construction, expansion, or modification of the SWWP will not directly conflict with the Comprehensive Plan, or other applicable local, regional, and state master plans, including, but not limited to storm drainage and flood control plans and storm water quality plans and programs; (k) The SWWP promotes the efficient use of water. (1) The existing wastewater treatment facilities or water treatment facilities within the Town of Avon and which serve the service area must be at or near operational capacity, or will be within five (5) years from the date construction of the SWWP is initiated, based on then - current demographic trends. Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 12 (m) The proposed construction, expansion, or modification of the SWWP will not increase water pollution levels in violation of applicable federal, state, and local water quality control standards and will result in no net loss of wetland values and functions; (n) The applicant has the technical and financial ability to develop and operate the proposed project in a manner that is consistent with the permit conditions and the public health, safety and welfare. (o) The nature and scope of the SWWP will not compete with existing water or wastewater treatment services or create duplicative services within the Town boundaries. Request: The expansion involves constructing a new CEPC Facility, which in turn will increase the organic capacity of the Avon WWTP by twenty-five percent (25 %). The request will allow the Avon WWTP to increase the permitted organic waste load from the existing limit of 9,400 pounds per day (ppd) to 11,750 ppd of biological oxygen demand at standard five day test conditions (BOD The need for the expansion stems back to the winter months of 2008 -2009 when the Avon WWTP experienced two (2) periods of stronger than anticipated influent loading conditions. These occurrences combined with ERWSD planning documents dictated the need for the Avon WWTP expansion. Various alternatives were analyzed (Page 4 of Exhibit A) with most options requiring a portion of the existing Autothermal Thermophilic Aerobic Digestion (ATAD) process to be converted and combined with an additional process. In each instance the alternative options were cost prohibitive, with the most economical option nearing $9 million. The CEPC process was selected and in September, 2010, a pilot facility was constructed. The CEPC system will increase primary solids removal and reduce the quantity of secondary waste activated sludge (WAS) when the CEPC system is operation. The reduction in organic and solids loading on the existing activated sludge treatment process will effectively increase the liquid stream capacity, allowing for a twenty-five percent (25 %) increase in influent organic loading without having to expand the existing treatment process. The Avon WWTP has a current ATAD system that is the most limiting factor in increasing the plant capacity. The ATAD system is a solids stabilization process that intakes primary sludge and produces a Class A biosolids (i.e. compost) product. The inclusion of the CEPC system will help pre -treat the sludge and allow the ATAD system to be more efficient, which in turn allows a greater amount of primary sludge to be processed. All excess waste sludge from the Vail and Avon WWTPs that exceed the maximum amount the ATAD system can process are discharged into a sewer to the Edwards WWTP. The CEPC system will use a coagulant chemical that will be injected into the system during the initial stage of treatment. A variety of coagulants exist, but the Applicant is proposing to use Ferric Chloride (FeC1 The Applicant is proposing to store the chemical in two (2) double - walled tanks, each having a capacity of 1,550 gallons. The tanks are proposed to be located in an old chlorine storage room, which is no longer in use. Staff Analysis: As stated previously in this report, Staff hired Mike Lutz, Dewberry, as a consultant to provide an independent analysis of the proposed improvement. Mike Lutz was directed by Staff to review the proposed application to verify the proposal from ERWSD, but also to analyze how the improvements would affect the Town's main concerns of odor generation, water quality, and effect on the general health, safety and welfare. The Town's main concern with the proposed improvements to the Avon WWTP is odor generation. An increased amount of wastewater being processed at the Avon WWTP will increase the potential for odor generation. Based on the report from Mike Lutz, Dewberry, (Exhibit B) the CEPC system will work in conjunction with the additional odor mitigation systems of the Avon WWTP. The coagulant Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 13 will help prevent the release of odor compounds into the air and help reduce hydrogen sulfide corrosion of steel, concrete, mechanical and electrical equipment in or near the primary clarifiers. The Applicant is only proposing to use this process during peak seasonal times. Mike Lutz suggests that the Town could derive some additional odor control benefit if the CEPC system is also used as a rapid response to odor incidents. Page 12 of his report (Exhibit B), suggests that metering ferric chloride into the primary clarifiers when an odor incident occurs could reduce the odorous compounds significantly within a few hours of the chemical addition. An additional concern of the Town is the use of Ferric Chloride and its effect on water quality and impact on adjacent properties. Ferric Chloride is a corrosive, non - flammable chemical that has a health hazard of 3 and reactivity of 2, with both categories having a maximum number of 4. This chemical is commonly used worldwide dating back to the 1970s. Locally the chemical is used by the Southgate Sanitation District in Denver as well as the Littleton - Englewood WWTP. The chemical will be stored in double - walled tank which will help contain the chemical in case it corrodes the first wall of the tank. In addition to the double - walled tank, the chemical will be stored in an old chlorine storage room which is equipped with a concrete floor that drains to an existing abandoned chlorine contact basin. If the tanks fail the chemical will drain to this area and can be pumped to the headworks. As outlined in the ERWSD application (Exhibit A), the installation of a full -scale CEPC system along with bulk storage will help decrease the need for deliveries, thus reducing the impact on neighboring properties. Mike Lutz' report (Exhibit B) states the use of Ferric Chloride will have an impact on water quality as it will add dissolved solids to the effluent and increase salinity. This will have an adverse effect on freshwater aquatic life, however at the recommended dose the chloride concentration would increase by approximately 11 mg /L. This amount of increase when compared to typical concentrations of 400 to 500 mg /L in WWTP effluent is a negligible amount and the effect will not be significant. Financial Implications: This application was accompanied by an initial deposit of ten thousand dollars ($10,000) toward a processing fee. Staff has used a portion of this fee to hire Mike Lutz, Dewberry, to review the proposed expansion and provide a third -party analysis. In addition to hiring a consultant, Staff has been tracking hours to review and process this application. The combination of these review fees are less than the initial deposit and no additional fees will be necessary to finalize this permit. The remaining excess balance will be returned to the applicant within one hundred and twenty (120) days following the date on which the Council makes a final determination regarding the application. Recommendation: Staff recommends that Council approve the Second Reading of Ordinance No: 12 -06 Town Manager Comments: Exhibits: A. ERWSD Avon WWTP 1041 Permit Application Binder —March, 2012 B. Memorandum dated May 9, 2012 from Mike Lutz, Dewberry C. Ordinance No. 12 -06, Approving a permit for areas and activities of state and local interest (1041 Permit) for the ERWSD expansion of the Avon Watewater Treatment Plant. Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 14 Dewberry EXHIBIT B MEMORANDUM DATE: May 9, 2012 TO: Justin Hildreth and Jared Barnes, Town of Avon FROM: Mike Lutz SUBJECT: Avon Wastewater Treatment Plant CEPC Project 1041 Permit Review EXECUTIVE SUMMARY Eagle River Water and Sanitation District ( ERWSD) plans to construct a Chemically Enhanced Primary Clarification (CEPC) Facility at the Avon wastewater treatment plant (WWTP). ERWSD has submitted a 1041 Permit Application to the Town of Avon for proposed CEPC improvements at the Avon WWTP. The CEPC Facility will increase the organic capacity of the Avon WWTP by 25 percent. Key issues of concern to the Town for the proposed CEPC improvements include reliable operation of the Avon WWTP with increased waste loads, potential odor emissions from the WWTP, impact on water quality, traffic and noise impacts, and potential adverse impacts on property values. The proposed CEPC system will increase primary solids removal and reduce the quantity of secondary waste activated sludge (WAS) when the CEPC system is operating. The CEPC system will reduce the organic and solids loading on the existing activated sludge treatment process which will effectively increase the liquid stream capacity in the existing WWTP and allow a 25 percent increase in influent organic loading without expansion of the existing treatment processes. The Avon WWTP has sufficient capacity to thicken WAS and dewater biosolids that will be produced by the Avon ATAD (Autothermal Thennophilic Aerobic Digestion) reactors with and without CEPC system operation. The existing Avon ATAD system will be operated at its' current capacity by treating a constant daily amount of primary sludge (base load). All excess waste sludge from the Vail and Avon WWTPs that exceeds the Avon ATAD system capacity will discharge into the sewer to the Edwards WWTP. The recently upgraded Edwards WWTP has sufficient capacity to accept all of the anticipated waste solids from the Vail and Avon WWTPs. Operating the existing Avon ATAD system at a constant feed rate with primary sludge will improve performance of this ATAD system and reduce odor potential at the Avon WWTP site. Operation of the proposed CEPC system will reduce odor generation in the primary clarifiers, ATAD reactors, and biosolids dewatering building whenever the CEPC chemical metering system operates. The odor control systems at the Avon WWTP have proven capability to treat exhaust air odors effectively. The existing odor control systems are expected to achieve equal or better performance after implementing CEPC than previously. The proposed CEPC system will not create any appreciable traffic or noise impacts, and is not expected to adversely affect property values near the Avon WWTP. Page 1 of 17 May 2, 2012 Page 2 of 17 Based on the evaluation of the benefits and potential impacts of the proposed CEPC system, approval of the Avon WWTP 1041 Permit Application is recommended. INTRODUCTION Eagle River Water and Sanitation District (ERWSD) owns and operates the Avon Wastewater Treatment Plant (WWTP) under the Colorado Discharge Permit System (CDPS) Permit, No. CO- 0024431. The Avon WWTP is approaching its current rated organic loading capacity during seasonal peak loading conditions. ERWSD plans to construct new Chemically Enhanced Primary Clarification (CEPC) Facilities to increase the organic capacity rating of the Avon WWTP by 25 percent. ERWSD has submitted a 1041 Permit Application to the Town of Avon for proposed CEPC improvements at the Avon WWTP. This memorandum provides a technical evaluation of the proposed improvements at the Avon WWTP to assist the Town of Avon in reviewing the 1041 Permit Application. PROJECT UNDERSTANDING The ERWSD intends to construct facilities at the existing Avon WWTP to implement Chemically Enhanced Primary Clarification (CEPC). The CEPC facilities will have the ability to operate continuosly. However, ERWSD intends to operate the CEPC facilities only during seasonal peak loading periods which historically occur during the winter and summer holidays. The ERWSD will request a 25 percent increase in the permitted organic waste load for the Avon WWTP based on the reduced loading applied to the existing activated sludge treatment process. The ERWSD request will increase the permitted organic waste load from the existing limit of 9,400 pounds per day (ppd) to 11,750 ppd of biological oxygen demand at standard five day test conditions (BODO. The proposed CEPC improvements and the increase in permitted Table 1 - Avon WWTP Requested Capacity capacity for the existing WWTP will allow ERWSD to treat high seasonal peak waste loads without expanding the existing treatment processes at the existing Avon WWTP for several years. The permitted hydraulic capacity of the Avon WWTP will remain unchanged at 4.3 million gallons per day (mgd). The proposed CEPC improvements would decrease the organic waste loading to the existing activated sludge treatment process when the CEPC chemical addition facilities are in use. The decrease in the organic waste loading to the existing activated sludge system would result in an increase in the organic waste loading to the solids stabilization process. The Avon WWTP has an ATAD (Autothennal Thermophilic Aerobic Digestion) solids stabilization process. The ATAD process currently has the most limited capacity of any ` F 6 Dewberry y Hydraulic Organic Parameter Capacity, Capacity, mgd ppd BOD Current 4.3 9,400 Proposed 4.3 11,750 Increase, % None 25 million gallons per day (mgd). The proposed CEPC improvements would decrease the organic waste loading to the existing activated sludge treatment process when the CEPC chemical addition facilities are in use. The decrease in the organic waste loading to the existing activated sludge system would result in an increase in the organic waste loading to the solids stabilization process. The Avon WWTP has an ATAD (Autothennal Thermophilic Aerobic Digestion) solids stabilization process. The ATAD process currently has the most limited capacity of any ` F 6 Dewberry y May 2, 2012 Page 3 of 17 treatment process at the Avon WWTP. To accommodate the increased amount of waste sludge produced when the CEPC system operates, the ATAD system at the Avon WWTP would treat primary sludge up to its' current capacity during peak loading periods. All excess waste sludge which exceeds the treatment capacity of the Avon ATAD system, would be conveyed through an existing sewer from the Avon WWTP to the Edwards WWTP for treatment. The ATAD system at the Edwards WWTP was expanded and upgraded to provide the capacity to treat waste sludge from the Edwards WWTP and additional waste sludge from the Vail and Avon WWTPs during holidays and seasonal peak loading periods. 1041 REVIEW PROCESS The Town Council has designated site selection and construction of major new domestic water and sewage treatment systems and major extension of existing domestic water and sewage treatment systems as matters subject to review and approval through the 1041 review process. The following key issues are of concern to the Town for the proposed improvements to the Avon WWTP: ■ Capacity of the existing ATAD process to operate reliably with increased waste loads ■ Capacity of the existing biosolids dewatering and loading equipment to operate reliably with increased waste loads ■ Impact of CEPC improvements on odor emissions from the WWTP ■ Impact of CEPC improvements on effluent water quality ■ Traffic, noise, air and water pollution impacts ■ Adverse impacts on property values DOCUMENTS REVIEWED To develop this evaluation of the Avon WWTP CEPC improvements for the 1041 review process, the documents listed Table 2 were reviewed. Table 2 - Documents Reviewed for the 1041 Permit for the Avon WWTP CEPC improvements Documents Reviewed Author and Date 1041 Permit Application for Avon WWTP CEPC Project CH2M HILL, March 2012 Site Application for Avon WWTP, Regulation 22 CH2M HILL, March 2012 Avon WWTF Improvements Project Process Design Report Frachetti Engineering, Feb 2012 Basis of Design (30 %) memorandum for ferric chloride system CH2M HILL, March 7, 2012 Chemically Enhanced Primary Clarification Pilot Study Results CH2M HILL, May 27, 2011 Avon WWTP Capacity Evaluation and Re- Rating Study CH2M HILL, March 30, 2010 Avon CEPC Project Drawings CH2M HILL, Jan. 2010 CEPC Final Design Report CH2M HILL, Nov. 2009 Sewer Operations — Multi -year Financial Model Bernstein Assoc., Oct 5, 2011 2008 Wastewater Master Plan Update Kennedy- Jenks, Jan. 28, 2010 Avon Municipal Code, Chapter 7.40, 1041 Regulations Town of Avon, 2012 CDPS Permit Number CO- 0024431 for Avon WWTP, amended CDPHE, April 29, 2011 General Permit Number COG - 650000 for Sewage Sludge USEPA, Oct. 19, 2007 2002 Eagle River Water Quality Management Plan NWCCOG, 2002 Avon WWTP Odor Emissions Characterization Integra Engineering, Apr. 22, 1997 4 6 . 4.11 Dewberry- May 2, 2012 Page 4 of 17 MODIFICATIONS TO THE 1041 APPLICATION AND SITE APPLICATION FORM In the appendix to the 1041 Application, the original letter to CDPHE requested a 10 percent increase in BOD5 capacity for the CEPC improvements. To prevent having two different versions of the same document, this letter was submitted `as is'. After the original letter to CDPHE, further full -scale tests demonstrated that 25 to 30 percent additional BOD5 removal could be achieved. Therefore, the 1041 Application was revised to request an increase of 25 percent capacity from the current organic rating of 9,400 ppd to 11,750 ppd. The site application form in the 1041 Application was also revised to request an increase of 25 percent BOD5 capacity (11,750 ppd) for the Avon WWTP on page 1 of 9. The original 1041 permit application mistakenly included an outdated copy of the site application form which requested a 15 percent BOD5 increase to 10,810 ppd. DESIGN CAPACITY Site Approval 4004 lists the design capacity for the Avon WWTP as 4.3 million gallons per day (mgd) for hydraulic flow (30 -day average) and 9,400 pounds BOD5 per day for organic loading (30 -day average). The activated sludge treatment process at the Avon WWTP was originally rated for an organic loading 6,600 pounds BOD5 per day based on a volumetric loading criteria of 40 pounds BOD5 per 1,000 cubic feet of aeration basin volume. The design capacity for the Avon WWTP was increased to 9,400 pounds BOD5 per day in 1995 due to the capability of the new primary sedimentation basins and ATAD process to reduce the organic loading on the activated sludge treatment process. FLOws AND LOADS Flow and waste loads to the Avon WWTP vary throughout the year. Current average flow is approximately 2.1 mgd and peak day flows are 3.5 mgd. Table 3 summarizes future (year 2025) estimated influent flows and loads to the Avon WWTF for both a low growth rate (1.9 percent annually) and a high growth rate (4.1 percent annually) (Frachetti Engineering, Process Design Report, Feb. 2012). The proposed CEPC project does not rerate the hydraulic capacity of the Avon WWTP or provide treatment capacity for the projected 2025 flows and loads. Table 3 - Estimated Influent Flow and Loads for Year 2025 Parameter Influent Flow, mgd Mass Loads, ppd Low High BOD5 TSS NH3 Growth Growth Annual Growth, % 1.9 4.1 Annual Average 2.7 3.7 8,390 12,160 590 Winter Maximum Month 3.1 4.1 16,880 24,390 1,050 Peak Day 4.9 6.7 22,840 29,610 1,460 Summer Maximum Month -- 5.2 10,140 16,190 640 Peak Day 6.6 11,700 21,430 1 1 740 Source: Avon WWTF Improvements Project Process Design Report, Frachetti Engineering, Feb 2012. W Dewberry May 2, 2012 Page 5 of 17 FACILITY DESCRIPTION The Avon WWTP was upgraded in December 1996 to its current nominal hydraulic capacity of 4.3 mgd. The facility has a headworks process with mechanical screens and aerated grit chamber, rectangular primary clarifiers, activated sludge aeration basins, secondary clarifiers, tertiary submerged fixed -film nitrification cells, and ultraviolet disinfection prior to discharge to the Eagle River. Table 4 summarizes the existing Avon WWTP process units. Primary sludge is pumped to an autothermal thermophilic aerobic digestion (ATAD) process. Waste activated sludge produced at Avon WWTP is thickened by gravity belt thickeners (GBT) before being pumped into the ATAD reactors. The ATAD process produces a Class A biosolids product when the solids residence time (SRT) is sufficient. Filtrate produced by thickening and dewatering is stored in equalization basins prior to blending with primary effluent. Digested sludge is dewatered by centrifuges. The Vail WWTP is located upstream from the Avon WWTP. The Vail Maximum month capacity obtained from Avon WWTP Capacity Evaluation and Re- Rating Study, CH2M HILL, WWTP has no waste solids March 30, 2010). Secondary Clarifier capacity based on stabilization process and discharges Aeration Basin MLSS = 3500, SVI = 140. primary sludge and settled waste activated sludge (WAS) to a gravity sewer to the Avon WWTP. Primary sludge and settled WAS from Vail WWTP is captured and thickened in the Avon primary sedimentation basins and is pumped to the ATAD reactors along with the Avon primary sludge. The original pumped venturi aeration system installed in the ATAD reactors at the Avon WWTP had limited mixing capabilities for thick sludge and limited oxygen- transfer capabilities. Low dissolved oxygen concentrations in the ATAD reactors likely resulted in anoxic and anaerobic conditions which generated odors. The original pumped venturi aeration system was upgraded to a more robust jet mixing system to improve oxygen - transfer capabilities and reduce odor potential. In addition, the ATAD system at the Avon WWTP is now base loaded mainly with primary sludge at its rated capacity and excess peak WAS loads are diverted to the sewer for treatment at the Edwards WWTP. Base loading of the Avon ATAD system is expected to minimize potential for anoxic and anaerobic conditions and therefore to reduce odor potential in the ATAD exhaust air. Table 4 — Avon WWTP Process Units Process Number of units Volume, MG Maximum month capacity, mgd Mechanical bar screens 2 12.48 Aerated grit tanks 2 6.24 Primary Settling Basins 2 5.3 Aeration Basins 4 1.218 3.8 Secondary Clarifiers 2 4.0 Nitrification Cells 8 0.431 5.5 Equalization Basins 2 0.245 Ultraviolet disinfection 2 5.4 Gravity belt thickeners 2 7.5 ATAD Digesters 4 0.320 2.9 Dewatering centrifuges 2 7 Odor control biotower 1 Ozone contact chamber 1 Chemical Scrubbers 2 I�pl a• Dewberry May 2, 2012 Page 6 of 17 SOLIDS STABILIZATION AND RESIDUALS MANAGEMENT The Avon and Edwards WWTPs use autothermal thermophilic aerobic digestion (ATAD) to treat and stabilize waste sludge and produce Class A biosolids. The Vail WWTP has no biosolids stabilization or disposal capabilities. All waste solids from the Vail WWTP are transferred to the Avon WWTP through the sewer. The existing "first generation" ATAD system at the Avon WWTP was designed with a rated hydraulic capacity of 6.4 mgd based on a solids retention time (SRT) of approximately 7 days. However, the existing Avon ATAD system does not produce Class A biosolids during winter peak loading conditions which result in a short SRT. To achieve Class A biosolids during all months of the year using the current ATAD reactor volume (assuming 20 percent reduction in ATAD reactor volume due to normal grit deposition and foam), the existing ATAD system would need to be de -rated to a hydraulic capacity of 2.9 mgd (CH2M HILL, March 30, 2010). Alternatively, the existing ATAD system could be expanded to a "second generation" ATAD system utilizing a minimum SRT of 13 days and be upgraded with better mixing and operational control. Instead of upgrading the ATAD system at the Avon WWTP, ERWSD will send all excess biosolids, both primary sludge and waste activated sludge (WAS), from the Vail and Avon WWTPs to the Edwards WWTP. The primary sludge sent from the Avon facility downstream also includes the WAS from Vail WWTP, which has no biosolids stabilization or disposal capabilities. The existing ATAD system at the Avon WWTP will be base loaded mainly with primary sludge, which will improve perfonnance of this "first generation" ATAD system. The new larger "second generation" ATAD and solids processing facilities at the Edwards WWTP will handle the majority of the solids stabilization for the ERWSD service area. Waste solids from the Vail and Avon WWTPs can be treated by the new Edwards ATAD reactors are shown in Table 5. The Edwards WWTP is expected to produce Class A biosolids at maximum month conditions even with the additional flow and load from Avon. The Table 5 - Surplus Capacity at Edwards WWTP Edwards WWTP sludge stabilization capacity is based on 13,300 ppd maximum month loading, primary sludge thickening in a gravity thickener, and WAS thickening in Year Edwards WWTP Surplus Capacity, ppd ATAD Gravity Thickener 2012 6,464 1,994 2015 5,086 586 2020 2,789 rotary drum thickeners (RDTs) as designed Capacity for 13,300 ppd maximum month load. (CH2M HILL, 2009). Dewatered digested biosolids are trucked to the Biosolids Composting Facility (BCF) located near the Eagle County Landfill at Wolcott (located approximately 9 miles from the Edwards WWTP). The proximity of the Edwards WWTP to the landfill will minimize costs for hauling dewatered biosolids to the BCF. Dewatered digested biosolids are stored in windrows on a 2 acre concrete pad at the BCF site. During the dry season, biosolids windrows are mechanically turned over to produce a dried Class A product. The drying pad is not covered which limits the 0;�� Dewberry- May 2, 2012 Page 7 of 17 ability to dry the biosolids during wet winter and spring weather. Dried biosolids are given to local landscapers for soil amendment or to the landfill for use as cover. ODOR CONTROL FACILITIES The 1996 expansion of the Avon WWTP included a new 22,000 cfm packed bed chemical scrubber to treat odorous exhaust air from headworks building, primary clarifiers, GBT room, and the ATAD process. After startup of the ATAD process, the new 22,000 cfm chemical scrubber proved inadequate to prevent off -site odors. Post - startup testing revealed that the exhaust air from the ATAD process contained high concentrations of ammonia, up to 50 ppm of methyl mercaptan, 17 odorous sulfur compounds, and amine compounds (Integra Engineering, 1997). Several of these compounds were exhausted from the existing chemical scrubber with concentrations high enough to cause odors in the community. To mitigate off -site odor impacts, a multi -stage odor control system was constructed to treat the high strength ATAD exhaust. The ATAD multi -stage odor control system consists of a packed bed biological scrubber, an ozone contact chamber, and a 3 -stage chemical scrubber operating in series. The biological scrubber is wetted with secondary effluent which supports growth of a biofilm that reduces the concentration of all of the odorous sulfur compounds observed in the ATAD exhaust, except carbon disulfide. The biological scrubber removes approximately 95 percent of the hydrogen sulfide, 80 percent of the dimethyl disulfide, and 60 to 75 percent of the methyl mercaptan in the ATAD exhaust air. It also removes 30 to 70 percent of the dimethyl sulfide and up to half of the carbonyl sulfide. The ozone contactor and chemical scrubber remove nearly all of the remaining sulfide and mercaptan odors (Integra Engineering, 1997). Exhaust from the ATAD multi -stage scrubber system mixes with other foul air exhausts and discharges into the existing 22,000 cfm packed bed chemical scrubber. A new structural cover and exhaust air system was constructed to contain odorous emissions from the existing 60 -foot diameter biosolids dewatering filtrate storage tank. These modifications eliminated off -site odor impacts. Since the original multi -stage odor control system was installed at the Avon WWTP, it has been modified to remove bottle necks and provide additional standby equipment to enhance reliability. The original main foul air fan was replaced by two 50 -hp fans which allowed some booster fans to be removed while also maintaining negative pressure within the odor control system to prevent leakage. An ionizing odor control unit was installed in the biosolids truck loading bay. A separate odor control system was installed for the activated sludge aeration basins and nitrification cells, which reduced the exhaust air flow rate through the ATAD multi -stage odor control system to enhance odor treatment for the rest of the plant. To maintain aerobic conditions in the ATAD reactors consistently, the original venturi aerators in the ATAD reactors ';;;' Dewberry May 2, 2012 Page 8 of 17 were replaced with a jet mixing and aeration system. ERWSD plans to continue improving the odor control systems during the summer of 2012. Currently, all of the odor control systems at the Avon WWTP are operated continuously except for the ozone contactor in the ATAD multi -stage system. The addition of a jet mixing for aeration in the ATAD reactors reduced odor generation and enabled ERWSD to operate the odor control systems without needing to use the ozone system. The ozone system can be restarted at any time if needed. The chemical dosing required for the chemical scrubbers varies seasonally from approximately 100 gallons of sodium hypochlorite per day in the summer to 400 gallons per day in the winter. Odor Control Systems Monitoring. The odor control systems have been equipped with monitoring sensors which provide operational status and alarm capability to the plant supervisory control and data acquisition ( SCADA) system. The SCADA system accumulates real time data, calculates averages values, and stores this data in the i- Historian daily reports. This improved SCADA monitoring has allowed ERWSD to prevent odor releases and correct operational problems when they occur. Odor control data is accumulated in the SCADA system in real time. The air flow rate through the main chemical scrubber system and pH and oxidation - reduction potential (ORP) are monitored continuously. The pH and ORP alarms on the chemical scrubbers notify operations staff if these parameters deviate from the control set points. If odor control alarms occur during unstaffed times at night, the SCADA system notifies an auto dialer to call the on -call operator. ERWSD monitors and tracks daily hypochlorite usage for the chemical scrubbers, the amount of sodium hypochlorite on site, time of chemical deliveries, and quantities of chemical delivered. Daily hypochlorite usage for the chemical scrubbers has been collected, stored, and tracked on the annual process control spreadsheet (Avon Info) for over five years. Odor Complaint Log. The Avon WWTP staff investigates all odor complaints that are reported and promptly adjusts treatment units and odor control equipment to eliminate odors generated by the Avon WWTP. ERWSD has been responsive to each complaint and has assisted the Town in tracking several odor sources that did not originate at the WWTPs. In March 2012, ERWSD modified the odor response protocol to improve response efficiency and began compiling odor complaints in a single spreadsheet to track odor events and trends yearly. MLE SECONDARY PROCESS IMPROVEMENTS ERWSD plans to construct the proposed Secondary Treatment Aeration and MLE Improvements Project at the Avon WWTP in 2012. This project will replace existing fine pore diffusers in the activated sludge aeration basins and modify the existing system to operate as a Modified Ludzack- Ettinger (MLE) process (Frachetti Engineering, Process Design Report, February 2012). Existing aeration basin diffusers will be replaced with 4,608 new membrane disk diffusers. The proposed improvements will maintain the current rated hydraulic and organic capacities. An amendment to an existing Site Location Approval for the Avon WWTP was Dewberry �� y May 2, 2012 Page 9 of 17 submitted (dated February 2012) for the proposed NILE project. The MLE project will not modify the rated hydraulic or organic capacity of the facility. The MLE project is intended to improve the reliability and efficiency of the activated sludge process and to reduce effluent total inorganic nitrogen (TIN) to meet future effluent limits. This MLE upgrade would add internal mixed- liquor recirculation (IMLR) from the final aeration basin to an anoxic tank at the head of the activated sludge process. The anoxic tank would operate at a low dissolved oxygen (DO) concentration and would use carbon in the primary effluent as a food source for biological denitrification (to convert dissolved nitrate to nitrogen gas) of the nitrate in the recycled mixed liquor. Denitrification will decrease effluent TIN, reduce energy costs by decreasing aeration demand, recover about half of the alkalinity consumed during nitrification, and improve sludge settleability. The MLE improvements are intended to be operated seasonally when flows and loads to the activated sludge process are low enough to allow adequate volume and solids retention time (SRT) for BOD removal, nitrification (oxidation of ammonia to nitrate), and denitrification (conversion of nitrate to nitrogen gas). During seasonal peak flows, the activated sludge system would be operated as a conventional non - nitrifying process. Effluent ammonia concentrations will increase seasonally in the conventional non - nitrifying activated sludge operating mode due to the reduced aerobic SRT which would not sustain nitrification. ERWSD intends to divert excess primary sludge and WAS from the Vail and Avon WWTPs to new biosolids stabilization facilities at the Edwards WWTP. This approach is expected to reduce the effluent TIN at Avon to below the 2016 permitted value without modifying the existing Avon activated sludge process. Therefore, the addition of the MLE configuration is not required to meet the 2016 TIN permit. The MLE upgrade will be implemented to achieve other performance benefits which include improved sludge settling, reduced oxygen demand, reduced energy consumption, and increased alkalinity that will occur as a result of reducing the effluent TIN to the greatest extent possible within the existing bioreactor volume. CHEMICALLY ENHANCED PRIMARY CLARIFICATION (CEPC) ERWSD intends to construct chemical storage and metering facilities to implement chemically enhanced primary clarification (CEPC). Addition of coagulant chemicals such as ferric chloride (FeC1 ferric sulfate (Fe2(SO4)3), or alum (Al2(SO4)3) can increase capture efficiency of total suspended solids (TSS), BOD and phosphorus in the primary clarifiers. By removing higher percentages of the TSS and BOD5 in the primary clarifiers, the amount of waste transferred in the primary sludge to the ATAD reactors would increase and the amount of waste transferred in the primary effluent to the activated sludge treatment process would decrease. Chemical addition will be operated seasonally during the peak ski season and summer tourist season. CEPC will defer expansion of the activated sludge aeration basins needed for seasonal peak flows. Primary Clarifier Performance. The performance of the existing primary clarifiers is expected to change in the future as the proportion of waste activated sludge (WAS) from Vail which is discharged to the Avon WWTP declines from approximately 38 percent of the Avon influent TSS load in 2008 to only 23 percent of the Avon influent TSS load by 2030. This Vail waste Dewberry- May 2, 2012 Page 10 of 17 sludge has favorable settling properties resulting in 80 percent TSS removal that has been observed at the Avon WWTP. By 2030, the primary clarifier TSS removal is expected to decrease from 80 percent currently to approximately 60 percent removal. Adding a CEPC chemical feed system would maintain the high level of TSS removal currently being achieved in the primary clarifiers. The proposed CEPC system will maximize primary solids removal and counteract the effects of the decreasing proportion of Vail WAS in the Avon WWTP influent. The proposed CEPC system will also increase the hydraulic capacity of the two existing primary clarifiers, which will defer the need for a 3rd primary clarifier for the next 20- years. Secondary Treatment Process. The proposed CEPC system will maximize TSS and BOD capture efficiency in the primary clarifiers which will significantly reduce the organic and solids loading on the existing activated sludge treatment process. The reduced loading applied to the activated sludge treatment process will effectively increase the capacity in the existing system by maintaining a safe operating SRT for nitrification. Improved ATAD Performance. CEPC would increase the ratio of primary sludge to secondary WAS. This rebalancing of the influent organic load would benefit the activated sludge process and would reduce nuisance foaming in the ATAD reactors. Odor and Corrosion Control Benefits. Addition of ferric chloride or ferric sulfate to the primary clarifiers would prevent the release of odor compounds into the air and reduce hydrogen sulfide corrosion of steel, concrete, mechanical and electrical equipment in or near the primary clarifiers. Implementing CEPC would reduce odor potential in the primary clarifiers, ATAD reactors, and biosolids dewatering building. Deferred Biological Phosphorus Removal Upgrades. Addition of coagulant chemicals such as ferric salts can reduce phosphorus concentrations to less than 1 mg /L with low capital costs. Jar test graphs developed during CEPC pilot tests at the Avon WWTP showed that a ferric chloride dose of 30 mg /L or greater could reduce settled water ortho- phosphorus concentrations below 0.5 mg/L. The equipment required to implement CEPC consists of chemical storage, metering and mixing which have relatively low capital costs. CEPC would provide near term chemical phosphorus removal which would enhance treated effluent quality while also deferring construction of future biological phosphorus removal facilities and optimizing management of financial resources. Water Quality Impacts. Addition of coagulant chemicals such as ferric salts used in CEPC causes an increase in the dissolved solids (chloride or sulfate ions) in the effluent which increases salinity in the receiving stream. The quality of the water the receiving stream would be slightly impaired by the increased salinity which has an adverse effect on freshwater aquatic life. However, at the recommended 17 mg /L FeC1 dose for CEPC, the effluent chloride concentration would increase by approximately 11 mg /L. This amount of additional chloride in the treated effluent is not significant (< 3 percent) compared to the typical total dissolved solids (TDS) concentrations of 400 to 500 mg /L of TDS in the WWTP effluent. Municipal wastewater effluent will have TDS concentrations approximately 250 to 300 mg/L greater than the potable water source for that system. Dewberry May 2, 2012 Page 11 of 17 CEPC PILOT TEST RESULTS Results of CEPC pilot tests at the Avon WWTP are summarized in Table 6. The first phase of the full -scale CEPC pilot testing from December 15, 2010 to April 15, 2011 resulted in 75 -80 percent TSS removal and approximately 70 percent biochemical oxygen demand (BOD removal with chemical addition. The ferric chloride dose varied from 15 to 60 mg /L (optimum dose at 17 to 22 mg/L) combined with 1.25 mg /L anionic polymer. Due to the success of the first phase of pilot testing, a second phase of full -scale CEPC testing was started on February 16, 2012. Table 6 - CEPC Pilot Test Summary, Phase 1 Parameter Baseline (no CEPC) CEPC Increase (decrease) Pilot testing start date Dec 15, 2009 Dec 21, 2010 Pilot testing end date April 30, 2010 April 26, 2011 Optimum FeC1 dose, mg /L none 30 Polymer dose, mg /L 1.25 Primary Clarifier TSS removal, percent 52.5 79.5 27 Primary Clarifier BOD removal, percent 45.6 70.4 25-30 Aeration Basin BOD Loading, ppd 2,880 1,930 (33) DESIGN CRITERIA FOR CHEMICAL COAGULANTS ADDED TO PRIMARY CLARIFIERS Addition of chemical coagulants to primary clarifiers has recently been included in the most recent draft of the Colorado Design Criteria for Domestic Wastewater Treatment Works (Colorado Department of Public Health and Environment, March 2012). The design criteria require that pilot plant testing with chemical coagulants be conducted to determine acceptable primary clarifier surface overflow rates or be based on results of similar full scale applications. The Avon WWTP conducted pilot testing and full scale testing of addition of chemical coagulants to the Avon primary clarifiers during 2010, 2011 and 2012. Therefore, the Avon CEPC improvements will be in compliance with the new Colorado Design Criteria when they are adopted later in 2012. PROPOSED FULL SCALE CEPC FACILITIES The recommended FeC1 dose for CEPC at Avon WWTP is 17 mg /L. FeC13 storage tanks will be double - walled high density cross - linked polyethylene construction. Each FeC13 storage tank will contain 1,550 gallons for a total of 3,100 gallon storage capacity at 38 percent FeC1 concentration. At the recommended 17 mg /L FeC13 dose (24 gallons per day) and average influent flow of approximately 2.4 mgd, the proposed 3,100 gallons of chemical storage would provide a 129 day supply of ferric chloride. The shelf life of 38 percent ferric chloride is over 12 months when stored inside. lrg Dewberry May 2, 2012 Page 12 of 17 Ferric chloride is corrosive, non flammable, has a health hazard of 3 and reactivity of 2. Ferric chloride is a hazardous material under International Building Code (IBC). The amount stored that is exempt from code requirements in a closed system is 500 gallons with an increase to 1,000 gallons if in approved containers and room. Storage tanks for FeC1 will be located in an old chlorine storage room which is no longer needed since chlorine disinfection has been replaced by UV disinfection. Storage volume of 3,100 gallons of FeC1 will require an H4 occupancy per the 2009 IBC. The chemical storage room will need fire separation walls from adjacent areas and require anew fire sprinkler system. The existing concrete floor has a drain to the existing abandoned chlorine contact basin below. Ferric chloride that drains to the existing abandoned chlorine contact basin can be pumped to the headworks. FERRIC CHLORIDE FOR ODOR INCIDENT RESPONSE ERWSD currently intends to operate the CEPC metering facilities seasonally during the peak ski season and summer tourist season only. The Town could derive some additional odor control benefit if the CEPC system were also operated as a rapid response to odor incidents at the Avon WWTP. By metering ferric chloride or ferric sulfate into the primary clarifiers when an odor incident occurs, the release of odorous sulfur compounds into the air could be reduced significantly, probably within a few hours of starting the chemical addition. The CEPC system could provide an additional response method to terminate odor incidents relatively quickly when the root cause of the incident might take longer time to correct. Ferric chloride has been used for odor control in many wastewater collection systems and WWTPs. The Littleton - Englewood WWTP located in the Denver metropolitan area has successfully operated a ferric chloride metering system for many years to prevent odors at the primary clarifiers. The Southgate Sanitation District which is also located in the south Denver metropolitan area has a chemical metering station to control odors from the main interceptor sewers. The Southgate chemical metering station used ferric chloride for several years to control interceptor odors. CEPC EXPERIENCE AT OTHER WWTPs CEPC has been used for decades at many WWTPs worldwide. Representative full scale CEPC facilities are listed in Table 7. European development of CEPC technology started in the early 1970s mainly in Scandinavia to control algal blooms by reducing phosphorus in the effluent. More than two dozen WWTPs in Norway had implemented CEPC by the 1990s. The Metro Wastewater Reclamation District in Denver, Colorado has also used CEPC as an interim upgrade while constructing other improvements. ao Dewberry ,. May 2, 2012 Page 13 of 17 Table 7 — Representative Full Scale CEPC Facilities Facility Location Capacity, m d CEPC coagulant Point Loma WWTP San Diego, CA 240 iron salts Hyperion WWTP Los Angeles, CA 350 FeC1 Sutton Wastewater Reclamation Facility Cobb County, GA 60 FeC1 Deer Island WWTP Boston, MA 365 FeC1 Columbia Boulevard WWTP Portland, OR 300 FeC1 Greater Nanaimo Pollution Control Centre British Columbia, Canada 29 FeC1 Stonecutters Island Sewage Treatment Works Hong Kong, China 370 FeC1 DISCHARGE PERMIT COMPLIANCE SCHEDULES The current discharge permit for the Avon WWTP includes the compliance schedules summarized in Table 8. The compliance schedules are related to temperature monitoring in the Eagle River, Mixing Zone Study, TIN and arsenic discharge limits, and construction progress reports. None of these items are expected to affect the proposed CEPC improvements. Table 8 - Avon WWTP Discharge Permit Compliance Schedules Code I Event Description Due Date 04301 Install Temperature Certify continuous temperature monitoring equipment is 4/30/2011 Meters installed and operational. 50008 Submit Mixing Collect and analyze site - specific data to determine if the 1/1/2012, Zone Study Results facility qualifies for Mixing Zone Exclusion. If a low flow 1/1/2013 condition is not reached on the receiving water during the first year, submit study results the following year. CS011 Activities to Meet Submit a report summarizing the results of the nitrogen 1/31/2012, TIN.and Total study on the Eagle River. Also submit information on the 1/31/2013, Recoverable possible sources of arsenic and activities taken to 1/31/2014 Arsenic limits reduce or eliminate these sources. CS010 Status /Progress Report progress in selecting an alternative to meet final 1/31/2015 p ermit limitations. CS016 Complete On -Site Complete construction of facilities or other appropriate 12/31/2015 Construction actions to meet final discharge limitations. CONCLUSIONS Solids stabilization in the ATAD process was identified as a capacity limiting process at the Avon WWTP (Capacity Evaluation and Re- Rating Study, C112M HILL, March 30, 2010). To achieve Class A biosolids consistently, the hydraulic capacity of the existing Avon ATAD system will be de -rated and the system will be base loaded with primary sludge at a constant feed rate up to the de -rated capacity. All excess waste solids, both primary sludge and waste activated sludge (WAS), from the Vail and Avon WWTPs will be discharged into the sewer to the Edwards WWTP. Base loading the existing Avon ATAD system mainly with primary sludge will improve performance of this ATAD system and reduce potential to generate odors. Dewberry® May 2, 2012 Page 14 of 17 Since the original pumped venturi aeration system was replaced with a jet mixing system, the modified Avon ATAD reactors are expected to maintain the dissolved oxygen control set point and therefore to have reduced potential to generate odors. The proposed CEPC system will maximize removal of suspended solids in the primary clarifiers. When the CEPC system is operating, the quantity of primary sludge will increase and the quantity of secondary WAS will decrease. Because all excess primary sludge and WAS will be discharged into the sewer to the Edwards WWTP, operation of the proposed CEPC system will not increase the solids loading to the existing Avon ATAD system (which will be base loaded with primary sludge). Operation of the proposed CEPC system will reduce the release of odor compounds from the ATAD reactors and reduce hydrogen sulfide corrosion. Implementing CEPC would reduce odor and corrosion potential in the primary clarifiers, ATAD reactors, and biosolids dewatering building. The Avon WWTP has a number of odor control systems which have proven capability to treat exhaust air odors effectively. The proposed CEPC system will reduce odor generation in the primary clarifiers, ATAD reactors, and biosolids dewatering building whenever the CEPC chemical metering system is operating. The existing odor control systems are expected to achieve equal or better performance after implementing CEPC than previously. The proposed CEPC system will maximize TSS and BOD5 capture efficiency in the primary clarifiers which will significantly reduce the organic and solids loading on the existing activated sludge treatment process. The reduced loading applied to the secondary treatment process will effectively increase nitrification capacity in the existing activated sludge process by maintaining a sufficient operating SRT to maintain the nitrifying biomass. The existing Avon WWTP has sufficient process equipment capacity to thicken WAS and dewater biosolids that will be produced by the Avon ATAD reactors. The recently upgraded Edwards WWTP has sufficient ATAD reactor capacity and thickening and dewatering capacity to accept all of the anticipated waste solids from the Vail and Avon WWTPs. Operation of the proposed CEPC system at the recommended FeC1 dose would require less than 6 truck loads of FeC1 chemical per year, even if operated continuously. The minimal number of chemical truck deliveries will have no appreciable effect on noise at the Avon WWTP or on traffic through the Town. Based on the evaluation of the benefits and potential impacts of the proposed CEPC system, approval of the Avon WWTP 1041 Permit Application is recommended. R y1 Dewberry May 2, 2012 Page 15 of 17 ACRONYMS AND ABBREVIATIONS ATAD Autothermal Thennophilic Aerobic Digestion BCF Biosolids Composting Facility BOD Biological oxygen demand at standard five day test conditions CDPHE Colorado Department of Public Health and Environment CDPS Colorado Discharge Permit System CEPC Chemically Enhanced Primary Clarification DO dissolved oxygen ERWSD Eagle River Water and Sanitation District GBT gravity belt thickeners gpd gallons per day IBC International Building Code IMLR internal mixed- liquor recirculation mgd million gallons per day mg /L milligrams per liter MLE Modified Ludzack- Ettinger process NWCCOG Northwest Colorado Council of Governments ORP oxidation - reduction potential ppd pounds per day RDT rotary drum thickener SCADA supervisory control and data acquisition SRT solids residence time TDS total dissolved solids TIN total inorganic nitrogen TSS total suspended solids UV ultraviolet WAS waste activated sludge WWTP wastewater treatment plant �� Dewberry- May 2, 2012 Page 16 of 17 REFERENCES Chagnon, F. and Harleman, D. R. F. (2001) An Introduction to Chemically Enhanced Primary Treatment, Massachusetts Institute of Technology, Cambridge, Massachusetts. CH2M HILL (March 2012) 1041 Permit Application for Avon WWTP CEPC Project, Englewood, Colorado. CH2M HILL (March 2012) Site Application for Avon WWTP, Regulation 22, Englewood, Colorado. CH2M HILL (March 7, 2012) Avon Wastewater Treatment Plant 30% Design of Ferric Chloride Storage Facilities, Basis of Design Technical Memorandum, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (May 27, 2011) Chemically Enhanced Primary Clarification Pilot Study Results, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado. C112M HILL (March 30, 2010) Avon Wastewater Treatment Plant Capacity Evaluation and Re- Rating Study, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado.. CH2M HILL (January 2010) Avon WWTP Chemically Enhanced Primary Clarification Project Drawings, prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (November 2009) Avon Wastewater Treatment Plant Chemically Enhanced Primary Clarification (CEPC) Project - Final Design Report, prepared for Eagle River Water and Sanitation District, Englewood, Colorado. Colorado Department of Public Health and Environment (April 29, 2011) CDPS Permit Number CO- 0024431 for Avon WWTP, amended, expiration date January 31, 2016, issued by Janet Kieler, Permits Section Manager, Water Quality Control Division, Denver, Colorado. Colorado Department of Public Health and Environment (March 19, 2012) State of Colorado Design Criteria For Domestic Wastewater Treatment Works, WPC -DR -1- Draft for Review, Water Quality Control Division, Denver, Colorado. Frachetti Engineering (February 2012) Process Design Report Avon Wastewater Treatment Facility, Secondary Treatment Improvements Project, prepared for Eagle River Water and Sanitation District, Greenwood Village, Colorado. Integra Engineering (April 22, 1997) Avon WWTP Odor Emissions Characterization, report prepared for Eagle River Water and Sanitation District, Denver, Colorado. y1F Dewberry- May 2, 2012 Page 17 of 17 Kennedy -Jenks Consultants, Engineers and Scientists (January 28, 2010) 2008 Wastewater Master Plan Update, report prepared for Eagle River Water and Sanitation District, Lakewood, Colorado. Massachusetts Water Resources Authority (April 13, 2012) Renewable and Sustainable Energy Initiatives at Deer Island, 1ittD:// www. mwra. com/ 03sewerihtnil /renewableenertrydi.htn Boston, Massachusetts. Mills, Jeffrey A., Reardon, R. D., Chastain, C. E., Cameron, J. L., and Goodman, G. V. (October 2006) Chemically Enhanced Primary Treatment For a Large Water Reclamation Facility on a Constricted Site - Considerations for Design, Start -Up, and Operation, presented at the 2006 Water Environment Federation Annual Conference, Atlanta, Georgia. Parker, Denny S., Barnard, J., Daigger, G. T., Tekippe, R. J., and Wahlberg, E. J. (March 15, 2001) The Future of Chemically Enhanced Primary Treatment: Evolution Not Revolution, published by the International Water Association. Northwest Colorado Council of Governments (2002) 2002 Eagle River Water Quality Management Plan, Silverthorne, Colorado. Stan Bernstein and Associates, Inc. (October 5, 2011) Sewer Operations — Multi year Financial Model, report prepared for Eagle River Water and Sanitation District, Greenwood Village, Colorado. Town of Avon (2012) Avon Municipal Code, Chapter 7.40, 1041 Regulations, Avon, Colorado. USEPA (October 19, 2007) General Permit Number COG - 650000 for Sewage Sludge, issued by Regional Biosolids Program, USEPA Region 8, Denver, Colorado. Alf Dewberry EXHIBIT C TOWN OF AVON, COLORADO ORDINANCE 12 -06 SERIES OF 2012 AN ORDINANCE APPROVING A PERMIT FOR AREAS AND ACTIVITIES OF STATE AND LOCAL INTEREST (1041 PERMIT) FOR THE EAGLE RIVER WATER AND SANITATION DISTRICT FOR AN EXPANSION OF THE AVON WASTEWATER TREATMENT PLANT WHEREAS, the Town of Avon ( "Town") is a home rule authority municipal corporation and body politic organized under the laws of the State of Colorado and possessing the maximum powers, authority and privileges to which it is entitled under Colorado law; and WHEREAS, Chapter 7.40 of the Avon Municipal Code authorizes the Town to review permit requests for areas and activities of state and local interest (1041 Permits); and WHEREAS, Eagle River Water and Sanitation District ( "the Owner ") has submitted an application for a 1041 Permit to expand the Avon Wastewater Treatment Plant; and WHEREAS, pursuant to Section 7.40.660, Approval of permit application, Avon Municipal Code, the Town Council has considered the applicable review criteria; and WHEREAS, the Town Council held public hearings on May 22, 2012 and June 12, 2012 after posting notice of such hearing in accordance with the requirements of Section 7.40.250, Public notice requirements, Avon Municipal Code, and considered all comments provided before taking action; and WHEREAS, it is the Town Council's opinion that the health, safety and welfare of the citizens of the Town of Avon would be enhanced and promoted by the adoption of this ordinance; and WHEREAS, approval of this Ordinance on first reading is intended only to confirm that the Town Council desires to comply with the requirements of the Avon Home Rule Charter by setting a public hearing in order to provide the public an opportunity to present testimony and evidence regarding the application and that approval of this Ordinance on first reading does not constitute a representation that the Town Council, or any member of the Town Council, supports, approves, rejects, or denies this ordinance; NOW THEREFORE, BE IT ORDAINED BY THE TOWN COUNCIL OF THE TOWN OF AVON, COLORADO, the following: Section 1 Recitals Incorporated The above and foregoing recitals are incorporated herein by reference and adopted as findings and determinations of the Town Council. Ord 12 -06 1041 Permit for Avon W WTP Expansion May 22, 2012 Second Reading revision Page 1 of 3 Section 2 Approval of a 1041 Permit The 1041 Permit for the expansion of the Avon Wastewater Treatment Plant as outlined in the Staff Memorandum dated May 22, 2012 and June 12, 2012 is hereby approved with the following conditions: 1. In addition to its use during peak seasonal periods as determined by the Eagle River Water and Sanitation District, the Chemically Enhanced Primary Clarification system will also be operated as a rapid response to odor incidents at the Avon Wastewater Treatment Plant. Section 3 Severability If any provision of this Ordinance, or the application of such provision to any person or circumstance, is for any reason held to be invalid, such invalidity shall not affect other provisions or applications of this Ordinance which can be given effect without the invalid provision or application, and to this end the provisions of this Ordinance are declared to be severable. The Town Council hereby declares that it would have passed this Ordinance and each provision thereof, even though any one of the provisions might be declared unconstitutional or invalid. As used in this Section, the term "provision" means and includes any part, division, subdivision, section, subsection, sentence, clause or phrase; the term "application" means and includes an application of an ordinance or any part thereof, whether considered or construed alone or together with another ordinance or ordinances, or part thereof, of the Town. Section 4 Effective Date This Ordinance shall take effect thirty days after final adoption in accordance with Section 6.4 of the Avon Home Rule Charter. Section 5 Safety Clause The Town Council hereby finds, determines and declares that this Ordinance is promulgated under the general police power of the Town of Avon, that it is promulgated for the health, safety and welfare of the public, and that this Ordinance is necessary for the preservation of health and safety and for the protection of public convenience and welfare. The Town Council further determines that the Ordinance bears a rational relation to the proper legislative object sought to be obtained. Section 6 No Existinu Violation Affected Nothing in this Ordinance shall be construed to release, extinguish, alter, modify, or change in whole or in part any penalty, liability or right or affect any audit, suit, or proceeding pending in any court, or any rights acquired, or liability incurred, or any cause or causes of action acquired or existing which may have been incurred or obtained under any ordinance or provision hereby repealed or amended by this Ordinance. Any such ordinance or provision thereof so amended, repealed, or superseded by this Ordinance shall be treated and held as remaining in force for the purpose of sustaining any and all proper actions, suits, proceedings and prosecutions, for the enforcement of such penalty, liability, or right, and for the purpose of sustaining any judgment, decree or order which can or may be rendered, entered, or made in such actions, suits or proceedings, or prosecutions imposing, inflicting, or declaring such penalty or liability or enforcing such right, and shall be treated and held as remaining in force for the purpose of sustaining any and all proceedings, actions, hearings, and appeals pending before any court or administrative tribunal. Ord 12 -06 1041 Permit for Avon W WTP Expansion May 22, 2012 Second Reading revision Page 2 of 3 Section 7. Publication by Posting The Town Clerk is ordered to publish this Ordinance by posting notice of adoption of this Ordinance on final reading by title in at least three public places within the Town and posting at the office of the Town Clerk, which notice shall contain a statement that a copy of the ordinance in full is available for public inspection in the office of the Town Clerk during normal business hours. INTRODUCED, APPROVED, PASSED ON FIRST READING, ORDERED POSTED AND REFERRED TO PUBLIC HEARING and setting such public hearing for 5:30 on June 12, 2012 at the Council Chambers of the Avon Municipal Building, located at One Lake Street, Avon, Colorado, on May 22, 2012. Rich Carroll, Mayor Published by posting in at least three public places in Town and posting at the office of the Town Clerk at least seven days prior to final action by the Town Council. ATTEST: APPROVED AS TO FORM: Patty McKenny, Town Clerk Eric Heil, Town Attorney INTRODUCED, FINALLY APPROVED, AND PASSED ON SECOND READING, AND ORDERED PUBLISHED BY POSTING on June 12, 2012. Rich Carroll, Mayor Published by posting by title in at least three public places in Town and posting by title at the office of the Town Clerk. ATTEST: Patty McKenny, Town Clerk Ord 12- 061041 Permit for Avon W WTP Expansion May 22, 2012 Second Reading revision Page 3 of 3 To Honorable Mayor and Town Council From Jared Barnes, Planner I Thru Patty McKenny, Interim Town Manager -° Eric Heil, Town Attorney Date June 12, 2012 Meeting Re Second Reading: Ordinance No. 12 -06, Series 2012: An Ordinance Approving A Permit For Areas And Activities of State And Local Interest (1041 Permit) Avon Wastewater Treatment Plant Expansion — PUBLIC HARING Update: At the May 22, 2012 meeting, the Town Council discussed the proposed Avon Wastewater Treatment Plant expansion. Ultimately, the Council approved the first reading of Ordinance 12 -06 after discussion on the proposed project took place. The Council did express concern with the lack of referral sent to Northwest Colorado Council of Governments ( NWCOGG) Water Quality division, the Eagle River Watershed Council, and the Eagle County Environmental Health department. Staff has contacted these agencies and solicited feedback. Both NWCOGG Water Quality division and Eagle County Environmental Health department stated that they were aware of the proposed modifications to the plant and had signed off on the improvements as a part of the National Permit Discharge Effluent Standards (NPDES) and Colorado Discharge Permit System (CDPS) approval processes. Staff also discussed the proposed improvements with the Eagle River Watershed Council, who had no objections to the request. The Council also asked Staff to discuss the CEPC process with the other Wastewater Treatment Plants that have used or are currently using the process or Ferric Chloride. The Littleton - Englewood Wastewater Treatment Plant has used Ferric Chloride in the past, but currently uses Ferric Sulfide because they were noticing an increase in the metal content in their biosolids. The representative did state that Ferric Chloride would be considered in the future due to the ability to use a cleaner version than what was utilized in the past. Both the Metro Wastewater Reclamation District and Southgate Sanitation District have used this process successfully in the past. Neither District had any negative feedback from their use of the process. Summary: The Eagle River Water and Sanitation District (ERWSD) is proposing to expand the Avon Wastewater Treatment Plant (the Project). The Permit Application for Areas and Activities of State and Local Interest (1041 Permit) is submitted pursuant to the Town of Avon's 1041 Regulations ((Title 7, Chapter 7.40, Avon Development Code ( "ADC ")) which requires a permit for "major extensions of existing domestic water and sewage treatment systems ". This permit application requests approval to construct a Chemically Enhanced Primary Clarification (CEPC) Facility at the Avon Wastewater Treatment Plant (WWTP) and increase the Avon WWTP's organic capacity by twenty -five percent (25 %). The CEPC Facility will be located within the existing Avon WWTP's building footprint located at 950 W. Beaver Creek Blvd (the Property) which is zoned Public Facility (PF). Accompanying this memorandum is the complete Application, dated March, 2012 (Exhibit A). The Application document includes all of the submittal information required by the ADC, including but not limited to: executive summary; summary of alternatives; detailed plans and specifications; federal, state, and local permits and approvals; environmental impacts and mitigation; need for proposed project; and, technical and financial feasibility. Town Staff had concern over the lack of in -house expertise to review technical documents related to wastewater treatment facilities. Michael Lutz of Dewberry was chosen as a consultant to work with Staff and provide third -party review. A Memorandum dated May 9 2012 from Michael Lutz, Dewberry, summarizes their review and is attached as Exhibit B. The final attachment is Ordinance 12 -06 (Exhibit C) which would approve the Permit request with conditions and findings. Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 11 Process: Pre Application conference A pre - application conference with the Applicant to discuss the 1041 Regulations and the permit process was conducted on January 23, 2012. Application Submittal The application was determined to be complete on April 16, 2012, at which time all of the mandatory application copies were accepted by Staff. The submittal requirements are governed by, ADC Section 7.40.220, Application Submittal Requirements. Agency Referrals Outside agency referrals were solicited via e-mail with a link to the complete application on the Town's website ( www.avon.orq /referral on April 24, 2012. Agencies included in the referral were: Eagle County Planning Department, Eagle County School District, ECO Trails, Eagle River Fire Protection District, and Eagle County Health Service District. Staff has not received any comments from the referral agencies. Published Notice As required by ADC Section 7.40.250, Public Notice Requirements, a public notice was published, on April 22, 2012 in the Vail Daily newspaper, at least 30 days in advance of the Town Council public hearing. Public Hearing The formal permit hearing with Town Council is set for May 22, 2012. The Council shall either approve or deny the permit by acting on Ordinance 12 -06 at the hearing after all relevant testimony has been heard. Review Considerations: According to ADC Section 7.40.660, Approval of Permit Application, the Council shall consider the following: (a) All of the provisions of the 1041 Permit application procedure set forth in Article III of these Regulations have been complied with; (b) Demographic trends demonstrate a need for the Special Water and Wastewater Project (SWWP) in order to timely serve existing and future residents and businesses within the Town; (c) Desirable local and regional community land use patterns will not be disrupted due to the location of the proposed construction, expansion, or modification of the SWWP; (d) The construction, expansion or modification of all dams or other impoundment structures required by the SWWP, if any, will comply with engineering requirements specified by the Colorado Water Conservation Board and the Office of the State Engineer. (e) The proposed SWWP is not subject to significant risk from earthquakes, floods, fires, subsidence, expansive soils, avalanches, landslides, or other natural hazards. (f) The proposed SWWP will not present an unreasonable risk of exposure to toxic or hazardous substances within the impact area. (g) The proposed SWWP will not significantly deteriorate floodplains, wetlands or riparian areas in the impact area. (h) The proposed SWWP will not significantly degrade existing visual quality, noise and vibration levels, or odor levels in the impact area. (i) The proposed SWWP is technically and financially feasible. Q) The proposed construction, expansion, or modification of the SWWP will not directly conflict with the Comprehensive Plan, or other applicable local, regional, and state master plans, including, but not limited to storm drainage and flood control plans and storm water quality plans and programs; (k) The SWWP promotes the efficient use of water. (1) The existing wastewater treatment facilities or water treatment facilities within the Town of Avon and which serve the service area must be at or near operational capacity, or will be within five (5) years from the date construction of the SWWP is initiated, based on then - current demographic trends. Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 12 (m) The proposed construction, expansion, or modification of the SWWP will not increase water pollution levels in violation of applicable federal, state, and local water quality control standards and will result in no net loss of wetland values and functions; (n) The applicant has the technical and financial ability to develop and operate the proposed project in a manner that is consistent with the permit conditions and the public health, safety and welfare. (o) The nature and scope of the SWWP will not compete with existing water or wastewater treatment services or create duplicative services within the Town boundaries. Request: The expansion involves constructing a new CEPC Facility, which in turn will increase the organic capacity of the Avon WWTP by twenty-five percent (25 %). The request will allow the Avon WWTP to increase the permitted organic waste load from the existing limit of 9,400 pounds per day (ppd) to 11,750 ppd of biological oxygen demand at standard five day test conditions (BOD The need for the expansion stems back to the winter months of 200 8-2009 when the Avon WWTP experienced two (2) periods of stronger than anticipated influent loading conditions. These occurrences combined with ERWSD planning documents dictated the need for the Avon WWTP expansion. Various alternatives were analyzed (Page 4 of Exhibit A) with most options requiring a portion of the existing Autothermal Thermophilic Aerobic Digestion (ATAD) process to be converted and combined with an additional process. In each instance the alternative options were cost prohibitive, with the most economical option nearing $9 million. The CEPC process was selected and in September, 2010, a pilot facility was constructed. The CEPC system will increase primary solids removal and reduce the quantity of secondary waste activated sludge (WAS) when the CEPC system is operation. The reduction in organic and solids loading on the existing activated sludge treatment process will effectively increase the liquid stream capacity, allowing for a twenty-five percent (25 %) increase in influent organic loading without having to expand the existing treatment process. The Avon WWTP has a current ATAD system that is the most limiting factor in increasing the plant capacity. The ATAD system is a solids stabilization process that intakes primary sludge and produces a Class A biosolids (i.e. compost) product. The inclusion of the CEPC system will help pre -treat the sludge and allow the ATAD system to be more efficient, which in turn allows a greater amount of primary sludge to be processed. All excess waste sludge from the Vail and Avon WWTPs that exceed the maximum amount the ATAD system can process are discharged into a sewer to the Edwards WWTP. The CEPC system will use a coagulant chemical that will be injected into the system during the initial stage of treatment. A variety of coagulants exist, but the Applicant is proposing to use Ferric Chloride (FeC1 The Applicant is proposing to store the chemical in two (2) double - walled tanks, each having a capacity of 1,550 gallons. The tanks are proposed to be located in an old chlorine storage room, which is no longer in use. Staff Analysis: As stated previously in this report, Staff hired Mike Lutz, Dewberry, as a consultant to provide an independent analysis of the proposed improvement. Mike Lutz was directed by Staff to review the proposed application to verify the proposal from ERWSD, but also to analyze how the improvements would affect the Town's main concerns of odor generation, water quality, and effect on the general health, safety and welfare. The Town's main concern with the proposed improvements to the Avon WWTP is odor generation. An increased amount of wastewater being processed at the Avon WWTP will increase the potential for odor generation. Based on the report from Mike Lutz, Dewberry, (Exhibit B) the CEPC system will work in conjunction with the additional odor mitigation systems of the Avon WWTP. The coagulant Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 13 will help prevent the release of odor compounds into the air and help reduce hydrogen sulfide corrosion of steel, concrete, mechanical and electrical equipment in or near the primary clarifiers. The Applicant is only proposing to use this process during peak seasonal times. Mike Lutz suggests that the Town could derive some additional odor control benefit if the CEPC system is also used as a rapid response to odor incidents. Page 12 of his report (Exhibit B), suggests that metering ferric chloride into the primary clarifiers when an odor incident occurs could reduce the odorous compounds significantly within a few hours of the chemical addition. An additional concern of the Town is the use of Ferric Chloride and its effect on water quality and impact on adjacent properties. Ferric Chloride is a corrosive, non - flammable chemical that has a health hazard of 3 and reactivity of 2, with both categories having a maximum number of 4. This chemical is commonly used worldwide dating back to the 1970s. Locally the chemical is used by the Southgate Sanitation District in Denver as well as the Littleton - Englewood WWTP. The chemical will be stored in double - walled tank which will help contain the chemical in case it corrodes the first wall of the tank. In addition to the double - walled tank, the chemical will be stored in an old chlorine storage room which is equipped with a concrete floor that drains to an existing abandoned chlorine contact basin. If the tanks fail the chemical will drain to this area and can be pumped to the headworks. As outlined in the ERWSD application (Exhibit A), the installation of a full -scale CEPC system along with bulk storage will help decrease the need for deliveries, thus reducing the impact on neighboring properties. Mike Lutz' report (Exhibit B) states the use of Ferric Chloride will have an impact on water quality as it will add dissolved solids to the effluent and increase salinity. This will have an adverse effect on freshwater aquatic life, however at the recommended dose the chloride concentration would increase by approximately 11 mg /L. This amount of increase when compared to typical concentrations of 400 to 500 mg /L in WWTP effluent is a negligible amount and the effect will not be significant. Financial Implications: This application was accompanied by an initial deposit of ten thousand dollars ($10,000) toward a processing fee. Staff has used a portion of this fee to hire Mike Lutz, Dewberry, to review the proposed expansion and provide a third -party analysis. In addition to hiring a consultant, Staff has been tracking hours to review and process this application. The combination of these review fees are less than the initial deposit and no additional fees will be necessary to finalize this permit. The remaining excess balance will be returned to the applicant within one hundred and twenty (120) days following the date on which the Council makes a final determination regarding the application. Recommendation: Staff recommends that Council approve the Second Reading of Ordinance No: 12 -06 Town Manager Comments: Exhibits: A. ERWSD Avon WWTP 1041 Permit Application Binder —March, 2012 B. Memorandum dated May 9, 2012 from Mike Lutz, Dewberry C. Ordinance No. 12 -06, Approving a permit for areas and activities of state and local interest (1041 Permit) for the ERWSD expansion of the Avon Watewater Treatment Plant. Town Council Meeting May 22, 2012 — Ordinance 12 -06 Second Reading Page 14 . -. Dewberry EXHIBIT B MEMORANDUM DATE: May 9, 2012 TO: Justin Hildreth and Jared Barnes, Town of Avon FROM: Mike Lutz SUBJECT: Avon Wastewater Treatment Plant CEPC Project 1041 Permit Review EXECUTIVE SUMMARY Eagle River Water and Sanitation District ( ERWSD) plans to construct a Chemically Enhanced Primary Clarification (CEPC) Facility at the Avon wastewater treatment plant (WWTP). ERWSD has submitted a 1041 Permit Application to the Town of Avon for proposed CEPC improvements at the Avon WWTP. The CEPC Facility will increase the organic capacity of the Avon WWTP by 25 percent. Key issues of concern to the Town for the proposed CEPC improvements include reliable operation of the Avon WWTP with increased waste loads, potential odor emissions from the WWTP, impact on water quality, traffic and noise impacts, and potential adverse impacts on property values. The proposed CEPC system will increase primary solids removal and reduce the quantity of secondary waste activated sludge (WAS) when the CEPC system is operating. The CEPC system will reduce the organic and solids loading on the existing activated sludge treatment process which will effectively increase the liquid stream capacity in the existing WWTP and allow a 25 percent increase in influent organic loading without expansion of the existing treatment processes. The Avon WWTP has sufficient capacity to thicken WAS and dewater biosolids that will be produced by the Avon ATAD (Autothermal Thermophilic Aerobic Digestion) reactors with and without CEPC system operation. The existing Avon ATAD system will be operated at its' current capacity by treating a constant daily amount of primary sludge (base load). All excess waste sludge from the Vail and Avon WWTPs that exceeds the Avon ATAD system capacity will discharge into the sewer to the Edwards WWTP. The recently upgraded Edwards WWTP has sufficient capacity to accept all of the anticipated waste solids from the Vail and Avon WWTPs. Operating the existing Avon ATAD system at a constant feed rate with primary sludge will improve performance of this ATAD system and reduce odor potential at the Avon WWTP site. Operation of the proposed CEPC system will reduce odor generation in the primary clarifiers, ATAD reactors, and biosolids dewatering building whenever the CEPC chemical metering system operates. The odor control systems at the Avon WWTP have proven capability to treat exhaust air odors effectively. The existing odor control systems are expected to achieve equal or better performance after implementing CEPC than previously. The proposed CEPC system will not create any appreciable traffic or noise impacts, and is not expected to adversely affect property values near the Avon WWTP. Page 1 of 17 May 2, 2012 Page 2 of 17 Based on the evaluation of the benefits and potential impacts of the proposed CEPC system, approval of the Avon WWTP 1041 Permit Application is recommended. INTRODUCTION Eagle River Water and Sanitation District (ERWSD) owns and operates the Avon Wastewater Treatment Plant (WWTP) under the Colorado Discharge Permit System (CDPS) Permit, No. CO- 0024431. The Avon WWTP is approaching its current rated organic loading capacity during seasonal peak loading conditions. ERWSD plans to construct new Chemically Enhanced Primary Clarification (CEPC) Facilities to increase the organic capacity rating of the Avon WWTP by 25 percent. ERWSD has submitted a 1041 Permit Application to the Town of Avon for proposed CEPC improvements at the Avon WWTP. This memorandum provides a technical evaluation of the proposed improvements at the Avon WWTP to assist the Town of Avon in reviewing the 1041 Permit Application. PROJECT UNDERSTANDING The ERWSD intends to construct facilities at the existing Avon WWTP to implement Chemically Enhanced Primary Clarification (CEPC). The CEPC facilities will have the ability to operate continuosly. However, ERWSD intends to operate the CEPC facilities only during seasonal peak loading periods which historically occur during the winter and summer holidays. The ERWSD will request a 25 percent increase in the permitted organic waste load for the Avon WWTP based on the reduced loading applied to the existing activated sludge treatment process. The ERWSD request will increase the permitted organic waste load from the existing limit of 9,400 pounds per day (ppd) to 11,750 ppd of biological oxygen demand at standard five day test conditions (BODO. The proposed CEPC improvements and the increase in permitted Table 1 - Avon WWTP Requested Capacity capacity for the existing WWTP will allow ERWSD to treat high seasonal peak waste loads without expanding the existing treatment processes at the existing Avon WWTP for several years. The permitted hydraulic capacity of the Avon WWTP will remain unchanged at 4.3 million gallons per day (mgd). The proposed CEPC improvements would decrease the organic waste loading to the existing activated sludge treatment process when the CEPC chemical addition facilities are in use. The decrease in the organic waste loading to the existing activated sludge system would result in an increase in the organic waste loading to the solids stabilization process. The Avon WWTP has an ATAD (Autothermal Thermophilic Aerobic Digestion) solids stabilization process. The ATAD process currently has the most limited capacity of any Dewberry Hydraulic Organic Parameter Capacity, Capacity, mgd ppd BOD Current 4.3 9,400 Proposed 4.3 11,750 Increase, % None 25 million gallons per day (mgd). The proposed CEPC improvements would decrease the organic waste loading to the existing activated sludge treatment process when the CEPC chemical addition facilities are in use. The decrease in the organic waste loading to the existing activated sludge system would result in an increase in the organic waste loading to the solids stabilization process. The Avon WWTP has an ATAD (Autothermal Thermophilic Aerobic Digestion) solids stabilization process. The ATAD process currently has the most limited capacity of any Dewberry May 2, 2012 Page 3 of 17 treatment process at the Avon WWTP. To accommodate the increased amount of waste sludge produced when the CEPC system operates, the ATAD system at the Avon WWTP would treat primary sludge up to its' current capacity during peak loading periods. All excess waste sludge which exceeds the treatment capacity of the Avon ATAD system, would be conveyed through an existing sewer from the Avon WWTP to the Edwards WWTP for treatment. The ATAD system at the Edwards WWTP was expanded and upgraded to provide the capacity to treat waste sludge from the Edwards WWTP and additional waste sludge from the Vail and Avon WWTPs during holidays and seasonal peak loading periods. 1041 REVIEW PROCESS The Town Council has designated site selection and construction of major new domestic water and sewage treatment systems and major extension of existing domestic water and sewage treatment systems as matters subject to review and approval through the 1041 review process. The following key issues are of concern to the Town for the proposed improvements to the Avon WWTP: ■ Capacity of the existing ATAD process to operate reliably with increased waste loads ■ Capacity of the existing biosolids dewatering and loading equipment to operate reliably with increased waste loads ■ Impact of CEPC improvements on odor emissions from the WWTP ■ Impact of CEPC improvements on effluent water quality ■ Traffic, noise, air and water pollution impacts ■ Adverse impacts on property values DOCUMENTS REVIEWED To develop this evaluation of the Avon WWTP CEPC improvements for the 1041 review process, the documents listed Table 2 were reviewed. Table 2 - Documents Reviewed for the 1041 Permit for the Avon WWTP CEPC improvements Documents Reviewed Author and Date 1041 Permit Application for Avon WWTP CEPC Project CH2M HILL, March 2012 Site Application for Avon WWTP, Regulation 22 CH2M HILL, March 2012 Avon WWTF Improvements Project Process Design Report Frachetti Engineering, Feb 2012 Basis of Design (30 %) memorandum for ferric chloride system CH2M HILL, March 7, 2012 Chemically Enhanced Primary Clarification Pilot Study Results CH2M HILL, May 27, 2011 Avon WWTP Capacity Evaluation and Re- Rating Study CH2M HILL, March 30, 2010 Avon CEPC Project Drawings CH2M HILL, Jan. 2010 CEPC Final Design Report CH2M HILL, Nov. 2009 Sewer Operations — Multi -year Financial Model Bernstein Assoc., Oct 5, 2011 2008 Wastewater Master Plan Update Kennedy- Jenks, Jan. 28, 2010 Avon Municipal Code, Chapter 7.40, 1041 Regulations Town of Avon, 2012 CDPS Permit Number CO- 0024431 for Avon WWTP, amended CDPHE, April 29, 2011 General Permit Number COG - 650000 for Sewage Sludge USEPA, Oct. 19, 2007 2002 Eagle River Water Quality Management Plan NWCCOG, 2002 Avon WWTP Odor Emissions Characterization Integra Engineering, Apr. 22, 1997 Dewberry May 2, 2012 Page 4 of 17 MODIFICATIONS TO THE 1041 APPLICATION AND SITE APPLICATION FORM In the appendix to the 1041 Application, the original letter to CDPHE requested a 10 percent increase in BOD5 capacity for the CEPC improvements. To prevent having two different versions of the same document, this letter was submitted `as is'. After the original letter to CDPHE, further full -scale tests demonstrated that 25 to 30 percent additional BOD5 removal could be achieved. Therefore, the 1041 Application was revised to request an increase of 25 percent capacity from the current organic rating of 9,400 ppd to 11,750 ppd. The site application form in the 1041 Application was also revised to request an increase of 25 percent BOD capacity (11,750 ppd) for the Avon WWTP on page 1 of 9. The original 1041 permit application mistakenly included an outdated copy of the site application form which requested a 15 percent BOD increase to 10,810 ppd. DESIGN CAPACITY Site Approval 4004 lists the design capacity for the Avon WWTP as 4.3 million gallons per day (mgd) for hydraulic flow (30 -day average) and 9,400 pounds BOD5 per day for organic loading (30 -day average). The activated sludge treatment process at the Avon WWTP was originally rated for an organic loading 6,600 pounds BOD5 per day based on a volumetric loading criteria of 40 pounds BOD5 per 1,000 cubic feet of aeration basin volume. The design capacity for the Avon WWTP was increased to 9,400 pounds BOD5 per day in 1995 due to the capability of the new primary sedimentation basins and ATAD process to reduce the organic loading on the activated sludge treatment process. FLOws AND LOADS Flow and waste loads to the Avon WWTP vary throughout the year. Current average flow is approximately 2.1 mgd and peak day flows are 3.5 mgd. Table 3 summarizes future (year 2025) estimated influent flows and loads to the Avon WWTF for both a low growth rate (1.9 percent annually) and a high growth rate (4.1 percent annually) (Frachetti Engineering, Process Design Report, Feb. 2012). The proposed CEPC project does not rerate the hydraulic capacity of the Avon WWTP or provide treatment capacity for the projected 2025 flows and loads. Table 3 - Estimated Influent Flow and Loads for Year 2025 Parameter Influent Flow, mgd Mass Loads, ppd Low High BOD5 TSS NH3 Growth Growth Annual Growth, % 1.9 4.1 Annual Average 2.7 3.7 8,390 12,160 590 Winter Maximum Month 3.1 4.1 16,880 24,390 1,050 Peak Day 4.9 6.7 22,840 1 29,610 1,460 Summer Maximum Month -- 5.2 10,140 16,190 640 Peak Da -- 6.6 11,700 21,430 740 Source: Avon WWTF Improvements Project Process Design Report, Frachetti Engineering, Feb 2012. Dewberry May 2, 2012 Page 5 of 17 FACILITY DESCRIPTION The Avon WWTP was upgraded in December 1996 to its current nominal hydraulic capacity of 4.3 mgd. The facility has a headworks process with mechanical screens and aerated grit chamber, rectangular primary clarifiers, activated sludge aeration basins, secondary clarifiers, tertiary submerged fixed -film nitrification cells, and ultraviolet disinfection prior to discharge to the Eagle River. Table 4 summarizes the existing Avon WWTP process units. Primary sludge is pumped to an autothermal thermophilic aerobic digestion (ATAD) process. Waste activated sludge produced at Avon WWTP is thickened by gravity belt thickeners (GBT) before being pumped into the ATAD reactors. The ATAD process produces a Class A biosolids product when the solids residence time (SRT) is sufficient. Filtrate produced by thickening and dewatering is stored in equalization basins prior to blending with primary effluent. Digested sludge is dewatered by centrifuges. The Vail WWTP is located upstream from the Avon WWTP. The Vail Maximum month capacity obtained from Avon WWTP Capacity Evaluation and Re- Rating Study, CH2M HILL, WWTP has no waste solids March 30, 2010). Secondary Clarifier capacity based on stabilization process and discharges Aeration Basin MLSS = 3500, SVI = 140, primary sludge and settled waste activated sludge (WAS) to a gravity sewer to the Avon WWTP. Primary sludge and settled WAS from Vail WWTP is captured and thickened in the Avon primary sedimentation basins and is pumped to the ATAD reactors along with the Avon primary sludge. The original pumped venturi aeration system installed in the ATAD reactors at the Avon WWTP had limited mixing capabilities for thick sludge and limited oxygen - transfer capabilities. Low dissolved oxygen concentrations in the ATAD reactors likely resulted in anoxic and anaerobic conditions which generated odors. The original pumped venturi aeration system was upgraded to a more robust jet mixing system to improve oxygen - transfer capabilities and reduce odor potential. In addition, the ATAD system at the Avon WWTP is now base loaded mainly with primary sludge at its rated capacity and excess peak WAS loads are diverted to the sewer for treatment at the Edwards WWTP. Base loading of the Avon ATAD system is expected to minimize potential for anoxic and anaerobic conditions and therefore to reduce odor potential in the ATAD exhaust air. Table 4 — Avon WWTP Process Units Process Number of units Volume, MG Maximum month capacity, mgd Mechanical bar screens 2 12.48 Aerated grit tanks 2 6.24 Primary Settling Basins 2 5.3 Aeration Basins 4 1.218 3.8 Secondary Clarifiers 2 4.0 Nitrification Cells 8 0.431 5.5 Equalization Basins 2 0.245 Ultraviolet disinfection 2 5.4 Gravity belt thickeners 2 7.5 ATAD Digesters 4 0.320 2.9 Dewatering centrifuges 2 7 Odor control biotower 1 Ozone contact chamber 1 Chemical Scrubbers 2 411 161 Dewberry- May 2, 2012 Page 6 of 17 SOLIDS STABILIZATION AND RESIDUALS MANAGEMENT The Avon and Edwards WWTPs use autothermal thermophilic aerobic digestion (ATAD) to treat and stabilize waste sludge and produce Class A biosolids. The Vail WWTP has no biosolids stabilization or disposal capabilities. All waste solids from the Vail WWTP are transferred to the Avon WWTP through the sewer. The existing "first generation" ATAD system at the Avon WWTP was designed with a rated hydraulic capacity of 6.4 mgd based on a solids retention time (SRT) of approximately 7 days. However, the existing Avon ATAD system does not produce Class A biosolids during winter peak loading conditions which result in a short SRT. To achieve Class A biosolids during all months of the year using the current ATAD reactor volume (assuming 20 percent reduction in ATAD reactor volume due to normal grit deposition and foam), the existing ATAD system would need to be de -rated to a hydraulic capacity of 2.9 mgd (CH2M HILL, March 30, 2010). Alternatively, the existing ATAD system could be expanded to a "second generation" ATAD system utilizing a minimum SRT of 13 days and be upgraded with better mixing and operational control. Instead of upgrading the ATAD system at the Avon WWTP, ERWSD will send all excess biosolids, both primary sludge and waste activated sludge (WAS), from the Vail and Avon WWTPs to the Edwards WWTP. The primary sludge sent from the Avon facility downstream also includes the WAS from Vail WWTP, which has no biosolids stabilization or disposal capabilities. The existing ATAD system at the Avon WWTP will be base loaded mainly with primary sludge, which will improve performance of this "first generation" ATAD system. The new larger "second generation" ATAD and solids processing facilities at the Edwards WWTP will handle the majority of the solids stabilization for the ERWSD service area. Waste solids from the Vail and Avon WWTPs can be treated by the new Edwards ATAD reactors are shown in Table 5. The Edwards WWTP is expected to produce Class A biosolids at maximum month conditions even with the additional flow and load from Avon. The Table 5 - Surplus Capacity at Edwards WWTP Edwards WWTP sludge stabilization capacity is based on 13,300 ppd maximum month loading, primary sludge thickening in a gravity thickener, and WAS thickening in Year Edwards WWTP Surplus Capacity, ppd ATAD Gravity Thickener 2012 6,464 1,994 2015 5,086 586 2020 2,789 rotary drum thickeners (RDTs) as designed Capacity for 13,300 ppd maximum month load. (CH2M HILL, 2009). Dewatered digested biosolids are trucked to the Biosolids Composting Facility (BCF) located near the Eagle County Landfill at Wolcott (located approximately 9 miles from the Edwards WWTP). The proximity of the Edwards WWTP to the landfill will minimize costs for hauling dewatered biosolids to the BCF. Dewatered digested biosolids are stored in windrows on a 2 acre concrete pad at the BCF site. During the dry season, biosolids windrows are mechanically turned over to produce a dried Class A product. The drying pad is not covered which limits the 6 1, 6111 Dewberry May 2, 2012 Page 7 of 17 ability to dry the biosolids during wet winter and spring weather. Dried biosolids are given to local landscapers for soil amendment or to the landfill for use as cover. ODOR CONTROL FACILITIES The 1996 expansion of the Avon WWTP included a new 22,000 cfm packed bed chemical scrubber to treat odorous exhaust air from headworks building, primary clarifiers, GBT room, and the ATAD process. After startup of the ATAD process, the new 22,000 cfm chemical scrubber proved inadequate to prevent off -site odors. Post - startup testing revealed that the exhaust air from the ATAD process contained high concentrations of ammonia, up to 50 ppm of methyl mercaptan, 17 odorous sulfur compounds, and amine compounds (Integra Engineering, 1997). Several of these compounds were exhausted from the existing chemical scrubber with concentrations high enough to cause odors in the community. To mitigate off -site odor impacts, a multi -stage odor control system was constructed to treat the high strength ATAD exhaust. The ATAD multi -stage odor control system consists of a packed bed biological scrubber, an ozone contact chamber, and a 3 -stage chemical scrubber operating in series. The biological scrubber is wetted with secondary effluent which supports growth of a biofilm that reduces the concentration of all of the odorous sulfur compounds observed in the ATAD exhaust, except carbon disulfide. The biological scrubber removes approximately 95 percent of the hydrogen sulfide, 80 percent of the dimethyl disulfide, and 60 to 75 percent of the methyl mercaptan in the ATAD exhaust air. It also removes 30 to 70 percent of the dimethyl sulfide and up to half of the carbonyl sulfide. The ozone contactor and chemical scrubber remove nearly all of the remaining sulfide and mercaptan odors (Integra Engineering, 1997). Exhaust from the ATAD multi -stage scrubber system mixes with other foul air exhausts and discharges into the existing 22,000 cfm packed bed chemical scrubber. A new structural cover and exhaust air system was constructed to contain odorous emissions from the existing 60 -foot diameter biosolids dewatering filtrate storage tank. These modifications eliminated off -site odor impacts. Since the original multi -stage odor control system was installed at the Avon WWTP, it has been modified to remove bottle necks and provide additional standby equipment to enhance reliability. The original main foul air fan was replaced by two 50 -hp fans which allowed some booster fans to be removed while also maintaining negative pressure within the odor control system to prevent leakage. An ionizing odor control unit was installed in the biosolids truck loading bay. A separate odor control system was installed for the activated sludge aeration basins and nitrification cells, which reduced the exhaust air flow rate through the ATAD multi -stage odor control system to enhance odor treatment for the rest of the plant. To maintain aerobic conditions in the ATAD reactors consistently, the original venturi aerators in the ATAD reactors Dewberry May 2, 2012 Page 8 of 17 were replaced with a jet mixing and aeration system. ERWSD plans to continue improving the odor control systems during the summer of 2012. Currently, all of the odor control systems at the Avon WWTP are operated continuously except for the ozone contactor in the ATAD multi -stage system. The addition of a jet mixing for aeration in the ATAD reactors reduced odor generation and enabled ERWSD to operate the odor control systems without needing to use the ozone system. The ozone system can be restarted at any time if needed. The chemical dosing required for the chemical scrubbers varies seasonally from approximately 100 gallons of sodium hypochlorite per day in the summer to 400 gallons per day in the winter. Odor Control Systems Monitoring. The odor control systems have been equipped with monitoring sensors which provide operational status and alarm capability to the plant supervisory control and data acquisition (SCADA) system. The SCADA system accumulates real time data, calculates averages values, and stores this data in the i- Historian daily reports. This improved SCADA monitoring has allowed ERWSD to prevent odor releases and correct operational problems when they occur. Odor control data is accumulated in the SCADA system in real time. The air flow rate through the main chemical scrubber system and pH and oxidation - reduction potential (ORP) are monitored continuously. The pH and ORP alarms on the chemical scrubbers notify operations staff if these parameters deviate from the control set points. If odor control alarms occur during unstaffed times at night, the SCADA system notifies an auto dialer to call the on -call operator. ERWSD monitors and tracks daily hypochlorite usage for the chemical scrubbers, the amount of sodium hypochlorite on site, time of chemical deliveries, and quantities of chemical delivered. Daily hypochlorite usage for the chemical scrubbers has been collected, stored, and tracked on the annual process control spreadsheet (Avon Info) for over five years. Odor Complaint Log. The Avon WWTP staff investigates all odor complaints that are reported and promptly adjusts treatment units and odor control equipment to eliminate odors generated by the Avon WWTP. ERWSD has been responsive to each complaint and has assisted the Town in tracking several odor sources that did not originate at the WWTPs. In March 2012, ERWSD modified the odor response protocol to improve response efficiency and began compiling odor complaints in a single spreadsheet to track odor events and trends yearly. MLE SECONDARY PROCESS IMPROVEMENTS ERWSD plans to construct the proposed Secondary Treatment Aeration and MLE Improvements Project at the Avon WWTP in 2012. This project will replace existing fine pore diffusers in the activated sludge aeration basins and modify the existing system to operate as a Modified Ludzack - Ettinger (MLE) process (Frachetti Engineering, Process Design Report, February 2012). Existing aeration basin diffusers will be replaced with 4,608 new membrane disk diffusers. The proposed improvements will maintain the current rated hydraulic and organic capacities. An amendment to an existing Site Location Approval for the Avon WWTP was 0" Dewberry May 2, 2012 Page 9 of 17 submitted (dated February 2012) for the proposed MLE project. The MLE project will not modify the rated hydraulic or organic capacity of the facility. The MLE project is intended to improve the reliability and efficiency of the activated sludge process and to reduce effluent total inorganic nitrogen (TIN) to meet future effluent limits. This MLE upgrade would add internal mixed- liquor recirculation (IMLR) from the final aeration basin to an anoxic tank at the head of the activated sludge process. The anoxic tank would operate at a low dissolved oxygen (DO) concentration and would use carbon in the primary effluent as a food source for biological denitrification (to convert dissolved nitrate to nitrogen gas) of the nitrate in the recycled mixed liquor. Denitrification will decrease effluent TIN, reduce energy costs by decreasing aeration demand, recover about half of the alkalinity consumed during nitrification, and improve sludge settleability. The MLE improvements are intended to be operated seasonally when flows and loads to the activated sludge process are low enough to allow adequate volume and solids retention time (SRT) for BOD removal, nitrification (oxidation of ammonia to nitrate), and denitrification (conversion of nitrate to nitrogen gas). During seasonal peak flows, the activated sludge system would be operated as a conventional non - nitrifying process. Effluent ammonia concentrations will increase seasonally in the conventional non - nitrifying activated sludge operating mode due to the reduced aerobic SRT which would not sustain nitrification. ERWSD intends to divert excess primary sludge and WAS from the Vail and Avon WWTPs to new biosolids stabilization facilities at the Edwards WWTP. This approach is expected to reduce the effluent TIN at Avon to below the 2016 permitted value without modifying the existing Avon activated sludge process. Therefore, the addition of the MLE configuration is not required to meet the 2016 TIN permit. The MLE upgrade will be implemented to achieve other performance benefits which include improved sludge settling, reduced oxygen demand, reduced energy consumption, and increased alkalinity that will occur as a result of reducing the effluent TIN to the greatest extent possible within the existing bioreactor volume. CHEMICALLY ENHANCED PRIMARY CLARIFICATION (CEPC) ERWSD intends to construct chemical storage and metering facilities to implement chemically enhanced primary clarification (CEPC). Addition of coagulant chemicals such as ferric chloride (FeC1 ferric sulfate (Fe2(SO4) or alum (Al2(SO4)3) can increase capture efficiency of total suspended solids (TSS), BOD and phosphorus in the primary clarifiers. By removing higher percentages of the TSS and BOD5 in the primary clarifiers, the amount of waste transferred in the primary sludge to the ATAD reactors would increase and the amount of waste transferred in the primary effluent to the activated sludge treatment process would decrease. Chemical addition will be operated seasonally during the peak ski season and summer tourist season. CEPC will defer expansion of the activated sludge aeration basins needed for seasonal peak flows. Primary Clarifier Performance. The performance of the existing primary clarifiers is expected to change in the future as the proportion of waste activated sludge (WAS) from Vail which is discharged to the Avon WWTP declines from approximately 38 percent of the Avon influent TSS load in 2008 to only 23 percent of the Avon influent TSS load by 2030. This Vail waste Dewberry May 2, 2012 Page 10 of 17 sludge has favorable settling properties resulting in 80 percent TSS removal that has been observed at the Avon WWTP. By 2030, the primary clarifier TSS removal is expected to decrease from 80 percent currently to approximately 60 percent removal. Adding a CEPC chemical feed system would maintain the high level of TSS removal currently being achieved in the primary clarifiers. The proposed CEPC system will maximize primary solids removal and counteract the effects of the decreasing proportion of Vail WAS in the Avon WWTP influent. The proposed CEPC system will also increase the hydraulic capacity of the two existing primary clarifiers, which will defer the need for a 3rd primary clarifier for the next 20- years. Secondary Treatment Process. The proposed CEPC system will maximize TSS and BOD capture efficiency in the primary clarifiers which will significantly reduce the organic and solids loading on the existing activated sludge treatment process. The reduced loading applied to the activated sludge treatment process will effectively increase the capacity in the existing system by maintaining a safe operating SRT for nitrification. Improved ATAD Performance. CEPC would increase the ratio of primary sludge to secondary WAS. This rebalancing of the influent organic load would benefit the activated sludge process and would reduce nuisance foaming in the ATAD reactors. Odor and Corrosion Control Benefits. Addition of ferric chloride or ferric sulfate to the primary clarifiers would prevent the release of odor compounds into the air and reduce hydrogen sulfide corrosion of steel, concrete, mechanical and electrical equipment in or near the primary clarifiers. Implementing CEPC would reduce odor potential in the primary clarifiers, ATAD reactors, and biosolids dewatering building. Deferred Biological Phosphorus Removal Upgrades. Addition of coagulant chemicals such as ferric salts can reduce phosphorus concentrations to less than 1 mg /L with low capital costs. Jar test graphs developed during CEPC pilot tests at the Avon WWTP showed that a ferric chloride dose of 30 mg /L or greater could reduce settled water ortho- phosphorus concentrations below 0.5 mg /L. The equipment required to implement CEPC consists of chemical storage, metering and mixing which have relatively low capital costs. CEPC would provide near term chemical phosphorus removal which would enhance treated effluent quality while also deferring construction of future biological phosphorus removal facilities and optimizing management of financial resources. Water Quality Impacts. Addition of coagulant chemicals such as ferric salts used in CEPC causes an increase in the dissolved solids (chloride or sulfate ions) in the effluent which increases salinity in the receiving stream. The quality of the water the receiving stream would be slightly impaired by the increased salinity which has an adverse effect on freshwater aquatic life. However, at the recommended 17 mg/L FCC1 dose for CEPC, the effluent chloride concentration would increase by approximately 11 mg /L. This amount of additional chloride in the treated effluent is not significant (< 3 percent) compared to the typical total dissolved solids (TDS) concentrations of 400 to 500 mg /L of TDS in the WWTP effluent. Municipal wastewater effluent will have TDS concentrations approximately 250 to 300 mg /L greater than the potable water source for that system. wY Dewberry May 2, 2012 Page 11 of 17 CEPC PILOT TEST RESULTS Results of CEPC pilot tests at the Avon WWTP are summarized in Table 6. The first phase of the full -scale CEPC pilot testing from December 15, 2010 to April 15, 2011 resulted in 75 -80 percent TSS removal and approximately 70 percent biochemical oxygen demand (BOD removal with chemical addition. The ferric chloride dose varied from 15 to 60 mg /L (optimum dose at 17 to 22 mg /L) combined with 1.25 mg /L anionic polymer. Due to the success of the first phase of pilot testing, a second phase of full -scale CEPC testing was started on February 16, 2012. Table 6 - CEPC Pilot Test Summary, Phase 1 Parameter Baseline (no CEPC) CEPC Increase (decrease) Pilot testing start date Dec 15, 2009 Dec 21, 2010 Pilot testing end date April 30, 2010 April 26, 2011 Optimum FeC1 dose, mg /L none 30 Polymer dose, mg /L 1.25 Primary Clarifier TSS removal, percent 52.5 79.5 27 Primary Clarifier BOD removal, percent 45.6 70.4 25-30 Aeration Basin BOD Loading, ppd 2,880 1,930 (33) DESIGN CRITERIA FOR CHEMICAL COAGULANTS ADDED TO PRIMARY CLARIFIERS Addition of chemical coagulants to primary clarifiers has recently been included in the most recent draft of the Colorado Design Criteria for Domestic Wastewater Treatment Works (Colorado Department of Public Health and Environment, March 2012). The design criteria require that pilot plant testing with chemical coagulants be conducted to determine acceptable primary clarifier surface overflow rates or be based on results of similar full scale applications. The Avon WWTP conducted pilot testing and full scale testing of addition of chemical coagulants to the Avon primary clarifiers during 2010, 2011 and 2012. Therefore, the Avon CEPC improvements will be in compliance with the new Colorado Design Criteria when they are adopted later in 2012. PROPOSED FULL SCALE CEPC FACILITIES The recommended FeC1 dose for CEPC at Avon WWTP is 17 mg /L. FeC1 storage tanks will be double - walled high density cross - linked polyethylene construction. Each FeC13 storage tank will contain 1,550 gallons for a total of 3,100 gallon storage capacity at 38 percent FeC1 concentration. At the recommended 17 mg /L FeCl dose (24 gallons per day) and average influent flow of approximately 2.4 mgd, the proposed 3,100 gallons of chemical storage would provide a 129 day supply of ferric chloride. The shelf life of 38 percent ferric chloride is over 12 months when stored inside. Dewberry May 2, 2012 Page 12 of 17 Ferric chloride is corrosive, non flammable, has a health hazard of 3 and reactivity of 2. Ferric chloride is a hazardous material under International Building Code (IBC). The amount stored that is exempt from code requirements in a closed system is 500 gallons with an increase to 1,000 gallons if in approved containers and room. Storage tanks for FeC1 will be located in an old chlorine storage room which is no longer needed since chlorine disinfection has been replaced by UV disinfection. Storage volume of 3,100 gallons of FeC13 will require an 114 occupancy per the 2009 IBC. The chemical storage room will need fire separation walls from adjacent areas and require anew fire sprinkler system. The existing concrete floor has a drain to the existing abandoned chlorine contact basin below. Ferric chloride that drains to the existing abandoned chlorine contact basin can be pumped to the headworks. FERRIC CHLORIDE FOR ODOR INCIDENT RESPONSE ERWSD currently intends to operate the CEPC metering facilities seasonally during the peak ski season and summer tourist season only. The Town could derive some additional odor control benefit if the CEPC system were also operated as a rapid response to odor incidents at the Avon WWTP. By metering ferric chloride or ferric sulfate into the primary clarifiers when an odor incident occurs, the release of odorous sulfur compounds into the air could be reduced significantly, probably within a few hours of starting the chemical addition. The CEPC system could provide an additional response method to terminate odor incidents relatively quickly when the root cause of the incident might take longer time to correct. Ferric chloride has been used for odor control in many wastewater collection systems and WWTPS. The Littleton - Englewood WWTP located in the Denver metropolitan area has successfully operated a ferric chloride metering system for many years to prevent odors at the primary clarifiers. The Southgate Sanitation District which is also located in the south Denver metropolitan area has a chemical metering station to control odors from the main interceptor sewers. The Southgate chemical metering station used ferric chloride for several years to control interceptor odors. CEPC EXPERIENCE AT OTHER WWTPS CEPC has been used for decades at many WWTPs worldwide. Representative full scale CEPC facilities are listed in Table 7. European development of CEPC technology started in the early 1970s mainly in Scandinavia to control algal blooms by reducing phosphorus in the effluent. More than two dozen WWTPS in Norway had implemented CEPC by the 1990s. The Metro Wastewater Reclamation District in Denver, Colorado has also used CEPC as an interim upgrade while constructing other improvements. SOON, Dewberry May 2, 2012 Page 13 of 17 Table 7 — Representative Full Scale CEPC Facilities Facility Location Capacity, m d CEPC coagulant Point Loma WWTP San Diego, CA 240 iron salts Hyperion WWTP Los Angeles, CA 350 FeC1 Sutton Wastewater Reclamation Facility Cobb County, GA 60 FeCl Deer Island WWTP Boston, MA 365 FeC1 Columbia Boulevard WWTP Portland, OR 300 FeC1 Greater Nanaimo Pollution Control Centre British Columbia, Canada 29 FeC1 Stonecutters Island Sewage Treatment Works Hong Kong, China 370 FeC1 DISCHARGE PERMIT COMPLIANCE SCHEDULES The current discharge permit for the Avon WWTP includes the compliance schedules summarized in Table 8. The compliance schedules are related to temperature monitoring in the Eagle River, Mixing Zone Study, TIN and arsenic discharge limits, and construction progress reports. None of these items are expected to affect the proposed CEPC improvements. Table 8 - Avon WWTP Discharge Permit Compliance Schedules Code I Event Description Due Date 04301 Install Temperature Certify continuous temperature monitoring equipment is 4/30/2011 Meters installed and operational. 50008 Submit Mixing Collect and analyze site - specific data to determine if the 1/1/2012, Zone Study Results facility qualifies for Mixing Zone Exclusion. If a low flow 1/1/2013 condition is not reached on the receiving water during the first year, submit study results the following ear. CS011 Activities to Meet Submit a report summarizing the results of the nitrogen 1/31/2012, TIN.and Total study on the Eagle River. Also submit information on the 1/31/2013, Recoverable possible sources of arsenic and activities taken to 1/31/2014 Arsenic limits reduce or eliminate these sources. CS010 Status /Progress Report progress in selecting an alternative to meet final 1/31/2015 p ermit limitations. CS016 Complete On -Site Complete construction of facilities or other appropriate 12/31/2015 Construction actions to meet final discharge limitations. CONCLUSIONS Solids stabilization in the ATAD process was identified as a capacity limiting process at the Avon WWTP (Capacity Evaluation and Re- Rating Study, C142M HILL, March 30, 2010). To achieve Class A biosolids consistently, the hydraulic capacity of the existing Avon ATAD system will be de -rated and the system will be base loaded with primary sludge at a constant feed rate up to the de -rated capacity. All excess waste solids, both primary sludge and waste activated sludge (WAS), from the Vail and Avon WWTPs will be discharged into the sewer to the Edwards WWTP. Base loading the existing Avon ATAD system mainly with primary sludge will improve performance of this ATAD system and reduce potential to generate odors. ;:fir Dewberry- May 2, 2012 Page 14 of 17 Since the original pumped venturi aeration system was replaced with a jet mixing system, the modified Avon ATAD reactors are expected to maintain the dissolved oxygen control set point and therefore to have reduced potential to generate odors. The proposed CEPC system will maximize removal of suspended solids in the primary clarifiers. When the CEPC system is operating, the quantity of primary sludge will increase and the quantity of secondary WAS will decrease. Because all excess primary sludge and WAS will be discharged into the sewer to the Edwards WWTP, operation of the proposed CEPC system will not increase the solids loading to the existing Avon ATAD system (which will be base loaded with primary sludge). Operation of the proposed CEPC system will reduce the release of odor compounds from the ATAD reactors and reduce hydrogen sulfide corrosion. Implementing CEPC would reduce odor and corrosion potential in the primary clarifiers, ATAD reactors, and biosolids dewatering building. The Avon WWTP has a number of odor control systems which have proven capability to treat exhaust air odors effectively. The proposed CEPC system will reduce odor generation in the primary clarifiers, ATAD reactors, and biosolids dewatering building whenever the CEPC chemical metering system is operating. The existing odor control systems are expected to achieve equal or better performance after implementing CEPC than previously. The proposed CEPC system will maximize TSS and BOD5 capture efficiency in the primary clarifiers which will significantly reduce the organic and solids loading on the existing activated sludge treatment process. The reduced loading applied to the secondary treatment process will effectively increase nitrification capacity in the existing activated sludge process by maintaining a sufficient operating SRT to maintain the nitrifying biomass. The existing Avon WWTP has sufficient process equipment capacity to thicken WAS and dewater biosolids that will be produced by the Avon ATAD reactors. The recently upgraded Edwards WWTP has sufficient ATAD reactor capacity and thickening and dewatering capacity to accept all of the anticipated waste solids from the Vail and Avon WWTPs. Operation of the proposed CEPC system at the recommended FeC1 dose would require less than 6 truck loads of FeC1 chemical per year, even if operated continuously. The minimal number of chemical truck deliveries will have no appreciable effect on noise at the Avon WWTP or on traffic through the Town. Based on the evaluation of the benefits and potential impacts of the proposed CEPC system, approval of the Avon WWTP 1041 Permit Application is recommended. ya Dewberry May 2, 2012 Page 15 of 17 ACRONYMS AND ABBREVIATIONS ATAD Autothermal Thermophilic Aerobic Digestion BCF Biosolids Composting Facility BOD Biological oxygen demand at standard five day test conditions CDPHE Colorado Department of Public Health and Environment CDPS Colorado Discharge Permit System CEPC Chemically Enhanced Primary Clarification DO dissolved oxygen ERWSD Eagle River Water and Sanitation District GBT gravity belt thickeners gpd gallons per day IBC International Building Code IMLR internal mixed- liquor recirculation mgd million gallons per day mg /L milligrams per liter MLE Modified Ludzack- Ettinger process NWCCOG Northwest Colorado Council of Governments ORP oxidation - reduction potential ppd pounds per day RDT rotary drum thickener SCADA supervisory control and data acquisition SRT solids residence time TDS total dissolved solids TIN total inorganic nitrogen TSS total suspended solids UV ultraviolet WAS waste activated sludge WWTP wastewater treatment plant Dewberry May 2, 2012 Page 16 of 17 REFERENCES Chagnon, F. and Harleman, D. R. F. (2001) An Introduction to Chemically Enhanced Primary Treatment, Massachusetts Institute of Technology, Cambridge, Massachusetts. CH2M HILL (March 2012) 1041 Permit Application for Avon WWTP CEPC Project, Englewood, Colorado. CH2M HILL (March 2012) Site Application for Avon WWTP, Regulation 22, Englewood, Colorado. CH2M HILL (March 7, 2012) Avon Wastewater Treatment Plant 30% Design of Ferric Chloride Storage Facilities, Basis of Design Technical Memorandum, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (May 27, 2011) Chemically Enhanced Primary Clarification Pilot Study Results, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (March 30, 2010) Avon Wastewater Treatment Plant Capacity Evaluation and Re- Rating Study, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado.. C112M HILL (January 2010) Avon WWTP Chemically Enhanced Primary Clarification Project Drawings, prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (November 2009) Avon Wastewater Treatment Plant Chemically Enhanced Primary Clarification (CEPC) Project - Final Design Report, prepared for Eagle River Water and Sanitation District, Englewood, Colorado. Colorado Department of Public Health and Environment (April 29, 2011) CDPS Permit Number CO- 0024431 for Avon WWTP, amended, expiration date January 31, 2016, issued by Janet Kieler, Permits Section Manager, Water Quality Control Division, Denver, Colorado. Colorado Department of Public Health and Environment (March 19, 2012) State of Colorado Design Criteria For Domestic Wastewater Treatment Works, WPC -DR -1- Draft for Review, Water Quality Control Division, Denver, Colorado. Frachetti Engineering (February 2012) Process Design Report Avon Wastewater Treatment Facility, Secondary Treatment Improvements Project, prepared for Eagle River Water and Sanitation District, Greenwood Village, Colorado. Integra Engineering (April 22, 1997) Avon WWTP Odor Emissions Characterization, report prepared for Eagle River Water and Sanitation District, Denver, Colorado. Dewberry, May 2, 2012 Page 17 of 17 Kennedy -Jenks Consultants, Engineers and Scientists (January 28, 2010) 2008 Wastewater Master Plan Update, report prepared for Eagle River Water and Sanitation District, Lakewood, Colorado. Massachusetts Water Resources Authority (April 13, 2012) Renewable and Sustainable Energy Initiatives at Deer Island, : ti":// www. mwra. conv03sewer /litml /renewableenerQydi. Boston, Massachusetts. Mills, Jeffrey A., Reardon, R. D., Chastain, C. E., Cameron, J. L., and Goodman, G. V. (October 2006) Chemically Enhanced Primary Treatment For a Large Water Reclamation Facility on a Constricted Site - Considerations for Design, Start -Up, and Operation, presented at the 2006 Water Environment Federation Annual Conference, Atlanta, Georgia. Parker, Denny S., Barnard, J., Daigger, G. T., Tekippe, R. J., and Wahlberg, E. J. (March 15, 2001) The Future of Chemically Enhanced Primary Treatment: Evolution Not Revolution, published by the International Water Association. Northwest Colorado Council of Governments (2002) 2002 Eagle River Water Quality Management Plan, Silverthorne, Colorado. Stan Bernstein and Associates, Inc. (October 5, 2011) Sewer Operations — Multi year Financial Model, report prepared for Eagle River Water and Sanitation District, Greenwood Village, Colorado. Town of Avon (2012) Avon Municipal Code, Chapter 7.40, 1041 Regulations, Avon, Colorado. USEPA (October 19, 2007) General Permit Number COG - 650000 for Sewage Sludge, issued by Regional Biosolids Program, USEPA Region 8, Denver, Colorado. g1F Dewberry EXHIBIT C TOWN OF AVON, COLORADO ORDINANCE 12 -06 SERIES OF 2012 AN ORDINANCE APPROVING A PERMIT FOR AREAS AND ACTIVITIES OF STATE AND LOCAL INTEREST (1041 PERMIT) FOR THE EAGLE RIVER WATER AND SANITATION DISTRICT FOR AN EXPANSION OF THE AVON WASTEWATER TREATMENT PLANT WHEREAS, the Town of Avon ( "Town") is a home rule authority municipal corporation and body politic organized under the laws of the State of Colorado and possessing the maximum powers, authority and privileges to which it is entitled under Colorado law; and WHEREAS, Chapter 7.40 of the Avon Municipal Code authorizes the Town to review permit requests for areas and activities of state and local interest (1041 Permits); and WHEREAS, Eagle River Water and Sanitation District ( "the Owner ") has submitted an application for a 1041 Permit to expand the Avon Wastewater Treatment Plant; and WHEREAS, pursuant to Section 7.40.660, Approval of permit application, Avon Municipal Code, the Town Council has considered the applicable review criteria; and WHEREAS, the Town Council held public hearings on May 22, 2012 and June 12, 2012 after posting notice of such hearing in accordance with the requirements of Section 7.40.250, Public notice requirements, Avon Municipal Code, and considered all comments provided before taking action; and WHEREAS, it is the Town Council's opinion that the health, safety and welfare of the citizens of the Town of Avon would be enhanced and promoted by the adoption of this ordinance; and WHEREAS, approval of this Ordinance on first reading is intended only to confirm that the Town Council desires to comply with the requirements of the Avon Home Rule Charter by setting a public hearing in order to provide the public an opportunity to present testimony and evidence regarding the application and that approval of this Ordinance on first reading does not constitute a representation that the Town Council, or any member of the Town Council, supports, approves, rejects, or denies this ordinance; NOW THEREFORE, BE IT ORDAINED BY THE TOWN COUNCIL OF THE TOWN OF AVON, COLORADO, the following: Section 1 Recitals Incorporated The above and foregoing recitals are incorporated herein by reference and adopted as findings and determinations of the Town Council. Ord 12 -06 1041 Permit for Avon W WTP Expansion May 22, 2012 Second Reading revision Page 1 of 3 Section 2 Approval of a 1041 Permit The 1041 Permit for the expansion of the Avon Wastewater Treatment Plant as outlined in the Staff Memorandum dated May 22, 2012 and June 12, 2012 is hereby approved with the following conditions: 1. In addition to its use during peak seasonal periods as determined by the Eagle River Water and Sanitation District, the Chemically Enhanced Primary Clarification system will also be operated as a rapid response to odor incidents at the Avon Wastewater Treatment Plant. Section 3 Severability If any provision of this Ordinance, or the application of such provision to any person or circumstance, is for any reason held to be invalid, such invalidity shall not affect other provisions or applications of this Ordinance which can be given effect without the invalid provision or application, and to this end the provisions of this Ordinance are declared to be severable. The Town Council hereby declares that it would have passed this Ordinance and each provision thereof, even though any one of the provisions might be declared unconstitutional or invalid. As used in this Section, the term "provision" means and includes any part, division, subdivision, section, subsection, sentence, clause or phrase; the term "application" means and includes an application of an ordinance or any part thereof, whether considered or construed alone or together with another ordinance or ordinances, or part thereof, of the Town. Section 4 Effective Date This Ordinance shall take effect thirty days after final adoption in accordance with Section 6.4 of the Avon Home Rule Charter. Section 5 Safety Clause The Town Council hereby finds, determines and declares that this Ordinance is promulgated under the general police power of the Town of Avon, that it is promulgated for the health, safety and welfare of the public, and that this Ordinance is necessary for the preservation of health and safety and for the protection of public convenience and welfare. The Town Council further determines that the Ordinance bears a rational relation to the proper legislative object sought to be obtained. Section 6 No Existing Violation Affected Nothing in this Ordinance shall be construed to release, extinguish, alter, modify, or change in whole or in part any penalty, liability or right or affect any audit, suit, or proceeding pending in any court, or any rights acquired, or liability incurred, or any cause or causes of action acquired or existing which may have been incurred or obtained under any ordinance or provision hereby repealed or amended by this Ordinance. Any such ordinance or provision thereof so amended, repealed, or superseded by this Ordinance shall be treated and held as remaining in force for the purpose of sustaining any and all proper actions, suits, proceedings and prosecutions, for the enforcement of such penalty, liability, or right, and for the purpose of sustaining any judgment, decree or order which can or may be rendered, entered, or made in such actions, suits or proceedings, or prosecutions imposing, inflicting, or declaring such penalty or liability or enforcing such right, and shall be treated and held as remaining in force for the purpose of sustaining any and all proceedings, actions, hearings, and appeals pending before any court or administrative tribunal. Ord 12- 061041 Permit for Avon WWTP Expansion May 22, 2012 Second Reading revision Page 2 of 3 Section 7. Publication by Posting The Town Clerk is ordered to publish this Ordinance by posting notice of adoption of this Ordinance on final reading by title in at least three public places within the Town and posting at the office of the Town Clerk, which notice shall contain a statement that a copy of the ordinance in full is available for public inspection in the office of the Town Clerk during normal business hours. INTRODUCED, APPROVED, PASSED ON FIRST READING, ORDERED POSTED AND REFERRED TO PUBLIC HEARING and setting such public hearing for 5:30 on June 12, 2012 at the Council Chambers of the Avon Municipal Building, located at One Lake Street, Avon, Colorado, on May 22, 2012. Rich Carroll, Mayor Published by posting in at least three public places in Town and posting at the office of the Town Clerk at least seven days prior to final action by the Town Council. ATTEST: APPROVED AS TO FORM: Patty McKenny, Town Clerk Eric Heil, Town Attorney INTRODUCED, FINALLY APPROVED, AND PASSED ON SECOND READING, AND ORDERED PUBLISHED BY POSTING on June 12, 2012. Rich Carroll, Mayor Published by posting by title in at least three public places in Town and posting by title at the office of the Town Clerk. ATTEST: Patty McKenny, Town Clerk Ord 12- 061041 Permit for Avon WWTP Expansion May 22, 2012 Second Reading revision Page 3 of 3 To Honorable Mayor and Town Council From Jared Barnes, Planner I Thru Patty McKenny, Interim Town Manager Eric Heil, Town Attorney Date May 22, 2012 Meeting Re First Reading: Ordinance No. 12 -06, Series 2012: An Ordinance Approving A Permit For Areas And Activities of State And Local Interest (1041 Permit) Avon Wastewater Treatment Plant Expansion — PUBLIC HARING Summary: The Eagle River Water and Sanitation District (ERWSD) is proposing to expand the Avon Wastewater Treatment Plant (the Project). The Permit Application for Areas and Activities of State and Local Interest (1041 Permit) is submitted pursuant to the Town of Avon's 1041 Regulations ((Title 7, Chapter 7.40, Avon Development Code ( "ADC ")) which requires a permit for "major extensions of existing domestic water and sewage treatment systems ". This permit application requests approval to construct a Chemically Enhanced Primary Clarification (CEPC) Facility at the Avon Wastewater Treatment Plant (WWTP) and increase the Avon WWTP's organic capacity by twenty -five percent (25 %). The CEPC Facility will be located within the existing Avon WWTP's building footprint located at 950 W. Beaver Creek Blvd (the Property) which is zoned Public Facility (PF). Accompanying this memorandum is the complete Application, dated March, 2012 (Exhibit A). The Application document includes all of the submittal information required by the ADC, including but not limited to: executive summary; summary of alternatives; detailed plans and specifications; federal, state, and local permits and approvals; environmental impacts and mitigation; need for proposed project; and, technical and financial feasibility. Town Staff had concern over the lack of in -house expertise to review technical documents related to wastewater treatment facilities. Michael Lutz of Dewberry was chosen as a consultant to work with Staff and provide third -party review. A Memorandum dated May 9 2012 from Michael Lutz, Dewberry, summarizes their review and is attached as Exhibit B. The final attachment is Ordinance 12 -06 (Exhibit C) which would approve the Permit request with conditions and findings. Process: Pre Application conference A pre - application conference with the Applicant to discuss the 1041 Regulations and the permit process was conducted on January 23, 2012. Application Submittal The application was determined to be complete on April 16, 2012, at which time all of the mandatory application copies were accepted by Staff. The submittal requirements are governed by, ADC Section 7.40.220, Application Submittal Requirements. Agency Referrals Outside agency referrals were solicited via e -mail with a link to the complete application on the Town's website ( www.avon.orq /referral on April 24, 2012. Agencies included in the referral were: Eagle County Planning Department, Eagle County School District, ECO Trails, Eagle River Fire Protection District, and Eagle County Health Service District. Staff has not received any comments from the referral agencies. Published Notice As required by ADC Section 7.40.250, Public Notice Requirements, a public notice was published, on April 22, 2012 in the Vail Daily newspaper, at least 30 days in advance of the Town Council public hearing. Public Hearing The formal permit hearing with Town Council is set for May 22, 2012. The Council shall either approve or deny the permit by acting on Ordinance 12 -06 at the hearing after all relevant testimony has been heard. Town Council Meeting May 22, 2012 — Ordinance 12 -06 First Reading Page 11 Review Considerations: According to ADC Section 7.40.660, Approval of Permit Application, the Council shall consider the following: (a) All of the provisions of the 1041 Permit application procedure set forth in Article III of these Regulations have been complied with; (b) Demographic trends demonstrate a need for the Special Water and Wastewater Project (SWWP) in order to timely serve existing and future residents and businesses within the Town; (c) Desirable local and regional community land use patterns will not be disrupted due to the location of the proposed construction, expansion, or modification of the SWWP; (d) The construction, expansion or modification of all dams or other impoundment structures required by the SWWP, if any, will comply with engineering requirements specified by the Colorado Water Conservation Board and the Office of the State Engineer. (e) The proposed SWWP is not subject to significant risk from earthquakes, floods, fires, subsidence, expansive soils, avalanches, landslides, or other natural hazards. (f) The proposed SWWP will not present an unreasonable risk of exposure to toxic or hazardous substances within the impact area. (g) The proposed SWWP will not significantly deteriorate floodplains, wetlands or riparian areas in the impact area. (h) The proposed SWWP will not significantly degrade existing visual quality, noise and vibration levels, or odor levels in the impact area. (i) The proposed SWWP is technically and financially feasible. (j) The proposed construction, expansion, or modification of the SWWP will not directly conflict with the Comprehensive Plan, or other applicable local, regional, and state master plans, including, but not limited to storm drainage and flood control plans and storm water quality plans and programs; (k) The SWWP promotes the efficient use of water. (1) The existing wastewater treatment facilities. or water treatment facilities within the Town of Avon and which serve the service area must be at or near operational capacity, or will be within five (5) years from the date construction of the SWWP is initiated, based on then - current demographic trends. (m) The proposed construction, expansion, or modification of the SWWP will not increase water pollution levels in violation of applicable federal, state, and local water quality control standards and will result in no net loss of wetland values and functions; (n) The applicant has the technical and financial ability to develop and operate the proposed project in a manner that is consistent with the permit conditions and the public health, safety and welfare. (o) The nature and scope of the SWWP will not compete with existing water or wastewater treatment services or create duplicative services within the Town boundaries. Request: The expansion involves constructing a new CEPC Facility, which in turn will increase the organic capacity of the Avon WWTP by twenty -five percent (25 %). The request will allow the Avon WWTP to increase the permitted organic waste load from the existing limit of 9,400 pounds per day (ppd) to 11,750 ppd of biological oxygen demand at standard five day test conditions (BOD The need for the expansion stems back to the winter months of 2008 -2009 when the Avon WWTP experienced two (2) periods of stronger than anticipated influent loading conditions. These occurrences combined with ERWSD planning documents dictated the need for the Avon WWTP expansion. Various alternatives were analyzed (Page 4 of Exhibit A) with most options requiring a portion of the existing Autothermal Thermophilic Aerobic Digestion (ATAD) process to be converted and combined with an additional process. In each instance the alternative options were cost prohibitive, with the most economical option nearing $9 million. The CEPC process was selected and in September, 2010, a pilot facility was constructed. Town Council Meeting May 22, 2012 — Ordinance 12 -06 First Reading Page 12 The CEPC system will increase primary solids removal and reduce the quantity of secondary waste activated sludge (WAS) when the CEPC system is operation. The reduction in organic and solids loading on the existing activated sludge treatment process will effectively increase the liquid stream capacity, allowing for a twenty-five percent (25 %) increase in influent organic loading without having to expand the existing treatment process. The Avon WWTP has a current ATAD system that is the most limiting factor in increasing the plant capacity. The ATAD system is a solids stabilization process that intakes primary sludge and produces a Class A biosolids (i.e. compost) product. The inclusion of the CEPC system will help pre -treat the sludge and allow the ATAD system to be more efficient, which in turn allows a greater amount of primary sludge to be processed. All excess waste sludge from the Vail and Avon WWTPs that exceed the maximum amount the ATAD system can process are discharged into a sewer to the Edwards WWTP. The CEPC system will use a coagulant chemical that will be injected into the system during the initial stage of treatment. A variety of coagulants exist, but the Applicant is proposing to use Ferric Chloride (FeC1 The Applicant is proposing to store the chemical in two (2) double - walled tanks, each having a capacity of 1,550 gallons. The tanks are proposed to be located in an old chlorine storage room, which is no longer in use. Staff Analysis: As stated previously in this report, Staff hired Mike Lutz, Dewberry, as a consultant to provide an independent analysis of the proposed improvement. Mike Lutz was directed by Staff to review the proposed application to verify the proposal from ERWSD, but also to analyze how the improvements would affect the Town's main concerns of odor generation, water quality, and effect on the general health, safety and welfare. The Town's main concern with the proposed improvements to the Avon WWTP is odor generation. An increased amount of wastewater being processed at the Avon WWTP will increase the potential for odor generation. Based on the report from Mike Lutz, Dewberry, (Exhibit B) the CEPC system will work in conjunction with the additional odor mitigation systems of the Avon WWTP. The coagulant will help prevent the release of odor compounds into the air and help reduce hydrogen sulfide corrosion of steel, concrete, mechanical and electrical equipment in or near the primary clarifiers. The Applicant is only proposing to use this process during peak seasonal times. Mike Lutz suggests that the Town could derive some additional odor control benefit if the CEPC system is also used as a rapid response to odor incidents. Page 12 of his report (Exhibit B), suggests that metering ferric chloride into the primary clarifiers when an odor incident occurs could reduce the odorous compounds significantly within a few hours of the chemical addition. An additional concern of the Town is the use of Ferric Chloride and its effect on water quality and impact on adjacent properties. Ferric Chloride is a corrosive, non - flammable chemical that has a health hazard of 3 and reactivity of 2, with both categories having a maximum number of 4. This chemical is commonly used worldwide dating back to the 1970s. Locally the chemical is used by the Southgate Sanitation District in Denver as well as the Littleton - Englewood WWTP. The chemical will be stored in double - walled tank which will help contain the chemical in case it corrodes the first wall of the tank. In addition to the double - walled tank, the chemical will be stored in an old chlorine storage room which is equipped with a concrete floor that drains to an existing abandoned chlorine contact basin. If the tanks fail the chemical will drain to this area and can be pumped to the headworks. As outlined in the ERWSD application (Exhibit A), the installation of a full -scale CEPC system along with bulk storage will help decrease the need for deliveries, thus reducing the impact on neighboring properties. Mike Lutz' report (Exhibit B) states the use of Ferric Chloride will have an impact on water quality as it will add dissolved solids to the effluent and increase salinity. This will have an adverse effect on freshwater aquatic life, however at the recommended dose the chloride concentration would increase by approximately 11 mg /L. This amount of increase when compared to typical Town Council Meeting May 22, 2012 — Ordinance 12 -06 First Reading Page 13 concentrations of 400 to 500 mg /L in WWTP effluent is a negligible amount and the effect will not be significant. Financial Implications: This application was accompanied by an initial deposit of ten thousand dollars ($10,000) toward a processing fee. Staff has used a portion of this fee to hire Mike Lutz, Dewberry, to review the proposed expansion and provide a third -party analysis. In addition to hiring a consultant, Staff has been tracking hours to review and process this application. The combination of these review fees are less than the initial deposit and no additional fees will be necessary to finalize this permit. The remaining excess balance will be returned to the applicant within one hundred and twenty (120) days following the date on which the Council makes a final determination regarding the application. Recommendation: Staff recommends that Council approve the first reading of Ordinance No: 12 -06 and schedule a public hearing and second reading on Jun 12, 2012. Town Manager Comments: Exhibits: A. ERWSD Avon WWTP 1041 Permit Application Binder — March, 2012 B. Memorandum dated May 9, 2012 from Mike Lutz, Dewberry C. Ordinance No. 12 -06, Approving a permit for areas and activities of state and local interest (1041 Permit) for the ERWSD expansion of the Avon Watewater Treatment Plant. Town Council Meeting May 22, 2012 — Ordinance 12 -06 First Reading Page 14 it Dewberry EXHIBIT B MEMORANDUM DATE: May 9, 2012 TO: Justin Hildreth and Jared Barnes, Town of Avon FROM: Mike Lutz SUBJECT: Avon Wastewater Treatment Plant CEPC Project 1041 Permit Review EXECUTIVE SUMMARY Eagle River Water and Sanitation District ( ERWSD) plans to construct a Chemically Enhanced Primary Clarification (CEPC) Facility at the Avon wastewater treatment plant (V% WTP). ERWSD has submitted a 1041 Permit Application to the Town of Avon for proposed CEPC improvements at the Avon WWTP. The CEPC Facility will increase the organic capacity of the Avon WWTP by 25 percent. Key issues of concern to the Town for the proposed CEPC improvements include reliable operation of the Avon WWTP with increased waste loads, potential odor emissions from the WWTP, impact on water quality, traffic and noise impacts, and potential adverse impacts on property values. The proposed CEPC system will increase primary solids removal and reduce the quantity of secondary waste activated sludge (WAS) when the CEPC system is operating. The CEPC `- system will reduce the organic and solids loading on the existing activated sludge treatment process which will effectively increase the liquid stream capacity in the existing WWTP and allow a 25 percent increase in influent organic loading without expansion of the existing treatment processes. The Avon WWTP has sufficient capacity to thicken WAS and dewater biosolids that will be produced by the Avon ATAD (Autothermal Thermophilic Aerobic Digestion) reactors with and without CEPC system operation. The existing Avon ATAD system will be operated at its' current capacity by treating a constant daily amount of primary sludge (base load). All excess waste sludge from the Vail and Avon WWTPs that exceeds the Avon ATAD system capacity will discharge into the sewer to the Edwards WWTP. The recently upgraded Edwards WWTP has sufficient capacity to accept all of the anticipated waste solids from the Vail and Avon WWTPs. Operating the existing Avon ATAD system at a constant feed rate with primary sludge will improve performance of this ATAD system and reduce odor potential at the Avon WWTP site. Operation of the proposed CEPC system will reduce odor generation in the primary clarifiers, ATAD reactors, and biosolids dewatering building whenever the CEPC chemical metering system operates. The odor control systems at the Avon WWTP have proven capability to treat exhaust air odors effectively. The existing odor control systems are expected to achieve equal or better performance after implementing CEPC than previously. The proposed CEPC system will not create any appreciable traffic or noise impacts, and is not expected to adversely affect property values near the Avon WWTP. Page 1 of 17 May 2, 2012 Page 2 of 17 Based on the evaluation of the benefits and potential impacts of the proposed CEPC system, approval of the Avon WWTP 1041 Permit Application is recommended. INTRODUCTION Eagle River Water and Sanitation District ( ERWSD) owns and operates the Avon Wastewater Treatment Plant (WWTP) under the Colorado Discharge Permit System (CDPS) Permit, No. CO- 0024431. The Avon WWTP is approaching its current rated organic loading capacity during seasonal peak loading conditions. ERWSD plans to construct new Chemically Enhanced Primary Clarification (CEPC) Facilities to increase the organic capacity rating of the Avon WWTP by 25 percent. ERWSD has submitted a 1041 Permit Application to the Town of Avon for proposed CEPC improvements at the Avon WWTP. This memorandum provides a technical evaluation of the proposed improvements at the Avon WWTP to assist the Town of Avon in reviewing the 1041 Permit Application. PROJECT UNDERSTANDING The ERWSD intends to construct facilities at the existing Avon WWTP to implement Chemically Enhanced Primary Clarification (CEPC). The CEPC facilities will have the ability to operate continuosly. However, ERWSD intends to operate the CEPC facilities only during seasonal peak loading periods which historically occur during the winter and summer holidays. The ERWSD will request a 25 percent increase in the permitted organic waste load for the Avon WWTP based on the reduced loading applied to the existing activated sludge treatment process. The ERWSD request will increase the permitted organic waste load from the existing limit of 9,400 pounds per day (ppd) to 11,750 ppd of biological oxygen demand at standard five day test conditions (BOD The proposed CEPC improvements and the increase in permitted Table 1 - Avon WWTP Requested Capacity capacity for the existing WWTP will allow ERWSD to treat high seasonal peak waste loads without expanding the existing treatment processes at the existing Avon WWTP for several years. The permitted hydraulic capacity of the Avon WWTP will remain unchanged at 4.3 million gallons per day (mgd). The proposed CEPC improvements would decrease the organic waste loading to the existing activated sludge treatment process when the CEPC chemical addition facilities are in use. The decrease in the organic waste loading to the existing activated sludge system would result in an increase in the organic waste loading to the solids stabilization process. The Avon WWTP has an ATAD (Autothermal Thermophilic Aerobic Digestion) solids stabilization process. The ATAD process currently has the most limited capacity of any Y Dewberry Hydraulic Organic Parameter Capacity, Capacity, mgd ppd BOD Current 4.3 9,400 Proposed 4.3 11,750 Increase, % None 25 million gallons per day (mgd). The proposed CEPC improvements would decrease the organic waste loading to the existing activated sludge treatment process when the CEPC chemical addition facilities are in use. The decrease in the organic waste loading to the existing activated sludge system would result in an increase in the organic waste loading to the solids stabilization process. The Avon WWTP has an ATAD (Autothermal Thermophilic Aerobic Digestion) solids stabilization process. The ATAD process currently has the most limited capacity of any Y Dewberry May 2, 2012 Page 3 of 17 treatment process at the Avon WWTP. To accommodate the increased amount of waste sludge produced when the CEPC system operates, the ATAD system at the Avon WWTP would treat primary sludge up to its' current capacity during peak loading periods. All excess waste sludge which exceeds the treatment capacity of the Avon ATAD system, would be conveyed through an existing sewer from the Avon WWTP to the Edwards WWTP for treatment. The ATAD system at the Edwards WWTP was expanded and upgraded to provide the capacity to treat waste sludge from the Edwards WWTP and additional waste sludge from the Vail and Avon WWTPs during holidays and seasonal peak loading periods. 1041 REVIEW PROCESS The Town Council has designated site selection and construction of major new domestic water and sewage treatment systems and major extension of existing domestic water and sewage treatment systems as matters subject to review and approval through the 1041 review process. The following key issues are of concern to the Town for the proposed improvements to the Avon WWTP: • Capacity of the existing ATAD process to operate reliably with increased waste loads • Capacity of the existing biosolids dewatering and loading equipment to operate reliably with increased waste loads • Impact of CEPC improvements on odor emissions from the WWTP • Impact of CEPC improvements on effluent water quality • Traffic, noise, air and water pollution impacts • Adverse impacts on property values DOCUMENTS REVIEWED To develop this evaluation of the Avon WWTP CEPC improvements for the 1041 review process, the documents listed Table 2 were reviewed. Table 2 - Documents Reviewed for the 1041 Permit for the Avon WWTP CEPC improvements Documents Reviewed Author and Date 1041 Permit Application for Avon WWTP CEPC Project CH2M HILL, March 2012 Site Application for Avon WWTP, Regulation 22 CH2M HILL, March 2012 Avon WWTF Improvements Project Process Design Report Frachetti Engineering, Feb 2012 Basis of Design (30 %) memorandum for ferric chloride system CH2M HILL, March 7, 2012 Chemically Enhanced Primary Clarification Pilot Study Results CH2M HILL, May 27, 2011 Avon WWTP Capacity Evaluation and Re- Rating Study CH2M HILL, March 30, 2010 Avon CEPC Project Drawings CH2M HILL, Jan. 2010 CEPC Final Design Report CH2M HILL, Nov. 2009 Sewer Operations — Multi -year Financial Model Bernstein Assoc., Oct 5, 2011 2008 Wastewater Master Plan Update Kennedy- Jenks, Jan. 28, 2010 Avon Municipal Code, Chapter 7.40, 1041 Regulations Town of Avon, 2012 CDPS Permit Number CO- 0024431 for Avon WWTP, amended CDPHE, April 29, 2011 General Permit Number COG - 650000 for Sewage Sludge USEPA, Oct. 19, 2007 2002 Eagle River Water Quality Management Plan NWCCOG, 2002 Avon WWTP Odor Emissions Characterization Integra Engineering, Apr. 22, 1997 Aoe 7 1, Dewberry May 2, 2012 Page 4 of 17 MODIFICATIONS TO THE 1041 APPLICATION AND SITE APPLICATION FORM In the appendix to the 1041 Application, the original letter to CDPHE requested a 10 percent increase in BOD5 capacity for the CEPC improvements. To prevent having two different versions of the same document, this letter was submitted `as is'. After the original letter to CDPHE, further full -scale tests demonstrated that 25 to 30 percent additional BOD removal could be achieved. Therefore, the 1041 Application was revised to request an increase of 25 percent capacity from the current organic rating of 9,400 ppd to 11,750 ppd. The site application form in the 1041 Application was also revised to request an increase of 25 percent BOD capacity (11,750 ppd) for the Avon WWTP on page 1 of 9. The original 1041 permit application mistakenly included an outdated copy of the site application form which requested a 15 percent BOD increase to 10,810 ppd. DESIGN CAPACITY Site Approval 4004 lists the design capacity for the Avon WWTP as 4.3 million gallons per day (mgd) for hydraulic flow (30 -day average) and 9,400 pounds BOD per day for organic loading (30 -day average). The activated sludge treatment process at the Avon WWTP was originally rated for an organic loading 6,600 pounds BOD5 per day based on a volumetric loading criteria of 40 pounds BOD5 per 1,000 cubic feet of aeration basin volume. The design capacity for the Avon WWTP was increased to 9,400 pounds BOD5 per day in 1995 due to the capability of the new primary sedimentation basins and ATAD process to reduce the organic loading on the activated sludge treatment process. FLOws AND LOADS Flow and waste loads to the Avon WWTP vary throughout the year. Current average flow is approximately 2.1 mgd and peak day flows are 3.5 mgd. Table 3 summarizes future (year 2025) estimated influent flows and loads to the Avon WWTF for both a low growth rate (1.9 percent annually) and a high growth rate (4.1 percent annually) (Frachetti Engineering, Process Design Report, Feb. 2012). The proposed CEPC project does not rerate the hydraulic capacity of the Avon WWTP or provide treatment capacity for the projected 2025 flows and loads. Table 3 - Estimated Influent Flow and Loads for Year 2025 Parameter Influent Flow, mgd Mass Loads, ppd Low High BOD5 TSS NH3 Growth Growth Annual Growth, % 1.9 4.1 Annual Average 2.7 3.7 8,390 12,160 590 Winter Maximum Month 3.1 4.1 16,880 24,390 1,050 Peak Day 4.9 6.7 22,840 29,610 1,460 Summer Maximum Month -- 5.2 10,140 16,190 640 Peak Day 6.6 11,700 21,430 740 Source: Avon WWTF Improvements Project Process Design Report, Frachetti Engineering, Feb 2012. ..; Dewberry- May 2, 2012 Page 5 of 17 FACILITY DESCRIPTION The Avon WWTP was upgraded in December 1996 to its current nominal hydraulic capacity of 4.3 mgd. The facility has a headworks process with mechanical screens and aerated grit chamber, rectangular primary clarifiers, activated sludge aeration basins, secondary clarifiers, tertiary submerged fixed -film nitrification cells, and ultraviolet disinfection prior to discharge to the Eagle River. Table 4 summarizes the existing Avon WWTP process units. Primary sludge is pumped to an autothermal thermophilic aerobic digestion (ATAD) process. Waste activated sludge produced at Avon WWTP is thickened by gravity belt thickeners (GBT) before being pumped into the ATAD reactors. The ATAD process produces a Class A biosolids product when the solids residence time (SRT) is sufficient. Filtrate produced by thickening and dewatering is stored in equalization basins prior to blending with primary effluent. Digested sludge is dewatered by centrifuges. The Vail WWTP is located upstream from the Avon WWTP. The Vail Maximum month capacity obtained from Avon WWTP Capacity Evaluation and Re- Rating Study, CH2M HILL, WWTP has no waste solids March 30, 2010). Secondary Clarifier capacity based on stabilization process and discharges Aeration Basin MLSS = 3500, SVI = 140. primary sludge and settled waste activated sludge (WAS) to a gravity sewer to the Avon WWTP. Primary sludge and settled WAS from Vail WWTP is captured and thickened in the Avon primary sedimentation basins and is pumped to the ATAD reactors along with the Avon primary sludge. The original pumped venturi aeration system installed in the ATAD reactors at the Avon WWTP had limited mixing capabilities for thick sludge and limited oxygen- transfer capabilities. Low dissolved oxygen concentrations in the ATAD reactors likely resulted in anoxic and anaerobic conditions which generated odors. The original pumped venturi aeration system was upgraded to a more robust jet mixing system to improve oxygen- transfer capabilities and reduce odor potential. In addition, the ATAD system at the Avon WWTP is now base loaded mainly with primary sludge at its rated capacity and excess peak WAS loads are diverted to the sewer for treatment at the Edwards WWTP. Base loading of the Avon ATAD system is expected to minimize potential for anoxic and anaerobic conditions and therefore to reduce odor potential in the ATAD exhaust air. Table 4 — Avon WWTP Process Units Process Number of units Volume, MG Maximum month capacity, mgd Mechanical bar screens 2 12.48 Aerated grit tanks 2 6.24 Primary Settling Basins 2 5.3 Aeration Basins 4 1.218 3.8 Secondary Clarifiers 2 4.0 Nitrification Cells 8 0.431 5.5 Equalization Basins 2 0.245 Ultraviolet disinfection 2 5.4 Gravity belt thickeners 2 7.5 ATAD Digesters 4 0.320 2.9 Dewatering centrifuges 2 7 Odor control biotower 1 Ozone contact chamber 1 Chemical Scrubbers 2 Dewberry May 2, 2012 Page 6 of 17 SOLIDS STABILIZATION AND RESIDUALS MANAGEMENT The Avon and Edwards WWTPs use autothermal thermophilic aerobic digestion (ATAD) to treat and stabilize waste sludge and produce Class A biosolids. The Vail WWTP has no biosolids stabilization or disposal capabilities. All waste solids from the Vail WWTP are transferred to the Avon WWTP through the sewer. The existing "first generation" ATAD system at the Avon WWTP was designed with a rated hydraulic capacity of 6.4 mgd based on a solids retention time (SRT) of approximately 7 days. However, the existing Avon ATAD system does not produce Class A biosolids during winter peak loading conditions which result in a short SRT. To achieve Class A biosolids during all months of the year using the current ATAD reactor volume (assuming 20 percent reduction in ATAD reactor volume due to normal grit deposition and foam), the existing ATAD system would need to be de -rated to a hydraulic capacity of 2.9 mgd (CH2M HILL, March 30, 2010). Alternatively, the existing ATAD system could be expanded to a "second generation" ATAD system utilizing a minimum SRT of 13 days and be upgraded with better mixing and operational control. Instead of upgrading the ATAD system at the Avon WWTP, ERWSD will send all excess biosolids, both primary sludge and waste activated sludge (WAS), from the Vail and Avon WWTPs to the Edwards WWTP. The primary sludge sent from the Avon facility downstream also includes the WAS from Vail WWTP, which has no biosolids stabilization or disposal capabilities. The existing ATAD system at the Avon WWTP will be base loaded mainly with primary sludge, which will improve performance of this "first generation" ATAD system. The new larger "second generation" ATAD and solids processing facilities at the Edwards WWTP will handle the majority of the solids stabilization for the ERWSD service area. Waste solids from the Vail and Avon WWTPs can be treated by the new Edwards ATAD reactors are shown in Table 5. The Edwards WWTP is expected to produce Class A biosolids at maximum month conditions even with the additional flow and load from Avon. The Table 5 - Surplus Capacity at Edwards WWTP Edwards WWTP sludge stabilization capacity is based on 13,300 ppd maximum month loading, primary sludge thickening in a gravity thickener, and WAS thickening in Year Edwards WWTP Sur lus Capacity d ATAD Gravity Thickener 2012 6,464 1,994 2015 5,086 586 2020 2,789 rotary drum thickeners (RDTs) as designed Capacity for 13,300 ppd maximum month load. (CH2M HILL, 2009). Dewatered digested biosolids are trucked to the Biosolids Composting Facility (BCF) located near the Eagle County Landfill at Wolcott (located approximately 9 miles from the Edwards WWTP). The proximity of the Edwards WWTP to the landfill will minimize costs for hauling dewatered biosolids to the BCF. Dewatered digested biosolids are stored in windrows on a 2 acre concrete pad at the BCF site. During the dry season, biosolids windrows are mechanically turned over to produce a dried Class A product. The drying pad is not covered which limits the Dewberry May 2, 2012 Page 7 of 17 ability to dry the biosolids during wet winter and spring weather. Dried biosolids are given to local landscapers for soil amendment or to the landfill for use as cover. ODOR CONTROL FACILITIES The 1996 expansion of the Avon WWTP included a new 22,000 cfin packed bed chemical scrubber to treat odorous exhaust air from headworks building, primary clarifiers, GBT room, and the ATAD process. After startup of the ATAD process, the new 22,000 cfin chemical scrubber proved inadequate to prevent off -site odors. Post - startup testing revealed that the exhaust air from the ATAD process contained high concentrations of ammonia, up to 50 ppm of methyl mercaptan, 17 odorous sulfur compounds, and amine compounds (Integra Engineering, 1997). Several of these compounds were exhausted from the existing chemical scrubber with concentrations high enough to cause odors in the community. To mitigate off -site odor impacts, a multi -stage odor control system was constructed to treat the high strength ATAD exhaust. The ATAD multi -stage odor control system consists of a packed bed biological scrubber, an ozone contact chamber, and a 3 -stage chemical scrubber operating in series. The biological scrubber is wetted with secondary effluent which supports growth of a biofilm that reduces the concentration of all of the odorous sulfur compounds observed in the ATAD exhaust, except carbon disulfide. The biological scrubber removes approximately 95 percent of the hydrogen sulfide, 80 percent of the dimethyl disulfide, and 60 to 75 percent of the methyl mercaptan in the ATAD exhaust air. It also removes 30 to 70 percent of the dimethyl sulfide and up to half of the carbonyl sulfide. The ozone contactor and chemical scrubber remove nearly all of the remaining sulfide and mercaptan odors (Integra Engineering, 1997). Exhaust from the ATAD multi -stage scrubber system mixes with other foul air exhausts and discharges into the existing 22,000 cfin packed bed chemical scrubber. A new structural cover and exhaust air system was constructed to contain odorous emissions from the existing 60 -foot diameter biosolids dewatering filtrate storage tank. These modifications eliminated off -site odor impacts. Since the original multi -stage odor control system was installed at the Avon WWTP, it has been modified to remove bottle necks and provide additional standby equipment to enhance reliability. The original main foul air fan was replaced by two 50 -hp fans which allowed some booster fans to be removed while also maintaining negative pressure within the odor control system to prevent leakage. An ionizing odor control unit was installed in the biosolids truck loading bay. A separate odor control system was installed for the activated sludge aeration basins and nitrification cells, which reduced the exhaust air flow rate through the ATAD multi -stage odor control system to enhance odor treatment for the rest of the plant. To maintain aerobic conditions in the ATAD reactors consistently, the original venturi aerators in the ATAD reactors Dewberry May 2, 2012 Page 8 of 17 were replaced with a jet mixing and aeration system. ERWSD plans to continue improving the odor control systems during the summer of 2012. Currently, all of the odor control systems at the Avon WWTP are operated continuously except for the ozone contactor in the ATAD multi -stage system. The addition of a jet mixing for aeration in the ATAD reactors reduced odor generation and enabled ERWSD to operate the odor control systems without needing to use the ozone system. The ozone system can be restarted at any time if needed. The chemical dosing required for the chemical scrubbers varies seasonally from approximately 100 gallons of sodium hypochlorite per day in the summer to 400 gallons per day in the winter. Odor Control Systems Monitoring. The odor control systems have been equipped with monitoring sensors which provide operational status and alarm capability to the plant supervisory control and data acquisition (SCADA) system. The SCADA system accumulates real time data, calculates averages values, and stores this data in the i- Historian daily reports. This improved SCADA monitoring has allowed ERWSD to prevent odor releases and correct operational problems when they occur. Odor control data is accumulated in the SCADA system in real time. The air flow rate through the main chemical scrubber system and pH and oxidation - reduction potential (ORP) are monitored continuously. The pH and ORP alarms on the chemical scrubbers notify operations staff if these parameters deviate from the control set points. If odor control alarms occur during unstaffed times at night, the SCADA system notifies an auto dialer to call the on -call operator. ERWSD monitors and tracks daily hypochlorite usage for the chemical scrubbers, the amount of sodium hypochlorite on site, time of chemical deliveries, and quantities of chemical delivered. Daily hypochlorite usage for the chemical scrubbers has been collected, stored, and tracked on the annual process control spreadsheet (Avon Info) for over five years. Odor Complaint Log. The Avon WWTP staff investigates all odor complaints that are reported and promptly adjusts treatment units and odor control equipment to eliminate odors generated by the Avon WWTP. ERWSD has been responsive to each complaint and has assisted the Town in tracking several odor sources that did not originate at the WWTPs. In March 2012, ERWSD modified the odor response protocol to improve response efficiency and began compiling odor complaints in a single spreadsheet to track odor events and trends yearly. MLE SECONDARY PROCESS IMPROVEMENTS ERWSD plans to construct the proposed Secondary Treatment Aeration and MLE Improvements Project at the Avon WWTP in 2012. This project will replace existing fine pore diffusers in the activated sludge aeration basins and modify the existing system to operate as a Modified Ludzack- Ettinger (MLE) process (Frachetti Engineering, Process Design Report, February 2012). Existing aeration basin diffusers will be replaced with 4,608 new membrane disk diffusers. The proposed improvements will maintain the current rated hydraulic and organic capacities. An amendment to an existing Site Location Approval for the Avon WWTP was ". _;: Dewberry- May 2, 2012 Page 9 of 17 submitted (dated February 2012) for the proposed MLE project. The MLE project will not modify the rated hydraulic or organic capacity of the facility. The MLE project is intended to improve the reliability and efficiency of the activated sludge process and to reduce effluent total inorganic nitrogen (TIN) to meet future effluent limits. This MLE upgrade would add internal mixed- liquor recirculation (IMLR) from the final aeration basin to an anoxic tank at the head of the activated sludge process. The anoxic tank would operate at a low dissolved oxygen (DO) concentration and would use carbon in the primary effluent as a food source for biological denitrification (to convert dissolved nitrate to nitrogen gas) of the nitrate in the recycled mixed liquor. Denitrification will decrease effluent TIN, reduce energy costs by decreasing aeration demand, recover about half of the alkalinity consumed during nitrification, and improve sludge settleability. The MLE improvements are intended to be operated seasonally when flows and loads to the activated sludge process are low enough to allow adequate volume and solids retention time (SRT) for BOD removal, nitrification (oxidation of ammonia to nitrate), and denitrification (conversion of nitrate to nitrogen gas). During seasonal peak flows, the activated sludge system would be operated as a conventional non - nitrifying process. Effluent ammonia concentrations will increase seasonally in the conventional non - nitrifying activated sludge operating mode due to the reduced aerobic SRT which would not sustain nitrification. ERWSD intends to divert excess primary sludge and WAS from the Vail and Avon WWTPs to new biosolids stabilization facilities at the Edwards WWTP. This approach is expected to reduce the effluent TIN at Avon to below the 2016 permitted value without modifying the existing Avon activated sludge process. Therefore, the addition of the MLE configuration is not required to meet the 2016 TIN permit. The MLE upgrade will be implemented to achieve other performance benefits which include improved sludge settling, reduced oxygen demand, reduced energy consumption, and increased alkalinity that will occur as a result of reducing the effluent TIN to the greatest extent possible within the existing bioreactor volume. CHEMICALLY ENHANCED PRIMARY CLARIFICATION (CEPC) ERWSD intends to construct chemical storage and metering facilities to implement chemically enhanced primary clarification (CEPC). Addition of coagulant chemicals such as ferric chloride (FeC1 ferric sulfate (Fe2(SO or alum (Al2(SO can increase capture efficiency of total suspended solids (TSS), BOD and phosphorus in the primary clarifiers. By removing higher percentages of the TSS and BOD5 in the primary clarifiers, the amount of waste transferred in the primary sludge to the ATAD reactors would increase and the amount of waste transferred in the primary effluent to the activated sludge treatment process would decrease. Chemical addition will be operated seasonally during the peak ski season and summer tourist season. CEPC will defer expansion of the activated sludge aeration basins needed for seasonal peak flows. Primary Clarifier Performance. The performance of the existing primary clarifiers is expected to change in the future as the proportion of waste activated sludge (WAS) from Vail which is discharged to the Avon WWTP declines from approximately 38 percent of the Avon influent TSS load in 2008 to only 23 percent of the Avon influent TSS load by 2030. This Vail waste is =:11 Dewberry e:_ May 2, 2012 Page 10 of 17 sludge has favorable settling properties resulting in 80 percent TSS removal that has been observed at the Avon WWTP. By 2030, the primary clarifier TSS removal is expected to decrease from 80 percent currently to approximately 60 percent removal. Adding a CEPC chemical feed system would maintain the high level of TSS removal currently being achieved in the primary clarifiers. The proposed CEPC system will maximize primary solids removal and counteract the effects of the decreasing proportion of Vail WAS in the Avon WWTP influent. The proposed CEPC system will also increase the hydraulic capacity of the two existing primary clarifiers, which will defer the need for a 3rd primary clarifier for the next 20- years. Secondary Treatment Process. The proposed CEPC system will maximize TSS and BOD capture efficiency in the primary clarifiers which will significantly reduce the organic and solids loading on the existing activated sludge treatment process. The reduced loading applied to the activated sludge treatment process will effectively increase the capacity in the existing system by maintaining a safe operating SRT for nitrification. Improved ATAD Performance. CEPC would increase the ratio of primary sludge to secondary WAS. This rebalancing of the influent organic load would benefit the activated sludge process and would reduce nuisance foaming in the ATAD reactors. Odor and Corrosion Control Benefits. Addition of ferric chloride or ferric sulfate to the primary clarifiers would prevent the release of odor compounds into the air and reduce hydrogen sulfide corrosion of steel, concrete, mechanical and electrical equipment in or near the primary clarifiers. Implementing CEPC would reduce odor potential in the primary clarifiers, ATAD reactors, and biosolids dewatering building. Deferred Biological Phosphorus Removal Upgrades. Addition of coagulant chemicals such as ferric salts can reduce phosphorus concentrations to less than 1 mg /L with low capital costs. Jar test graphs developed during CEPC pilot tests at the Avon WWTP showed that a ferric chloride dose of 30 mg /L or greater could reduce settled water ortho- phosphorus concentrations below 0.5 mg /L. The equipment required to implement CEPC consists of chemical storage, metering and mixing which have relatively low capital costs. CEPC would provide near term chemical phosphorus removal which would enhance treated effluent quality while also deferring construction of future biological phosphorus removal facilities and optimizing management of financial resources. Water Quality Impacts. Addition of coagulant chemicals such as ferric salts used in CEPC causes an increase in the dissolved solids (chloride or sulfate ions) in the effluent which increases salinity in the receiving stream. The quality of the water the receiving stream would be slightly impaired by the increased salinity which has an adverse effect on freshwater aquatic life. However, at the recommended 17 mg /L FeC1 dose for CEPC, the effluent chloride concentration would increase by approximately 11 mg /L. This amount of additional chloride in the treated effluent is not significant (< 3 percent) compared to the typical total dissolved solids (TDS) concentrations of 400 to 500 mg /L of TDS in the WWTP effluent. Municipal wastewater effluent will have TDS concentrations approximately 250 to 300 mg /L greater than the potable water source for that system. {"' Dewberry May 2, 2012 Page 11 of 17 CEPC PILOT TEST RESULTS Results of CEPC pilot tests at the Avon WWTP are summarized in Table 6. The first phase of the full -scale CEPC pilot testing from December 15, 2010 to April 15, 2011 resulted in 75 -80 percent TSS removal and approximately 70 percent biochemical oxygen demand (BODO removal with chemical addition. The ferric chloride dose varied from 15 to 60 mg/L (optimum dose at 17 to 22 mg /L) combined with 1.25 mg/L anionic polymer. Due to the success of the first phase of pilot testing, a second phase of full -scale CEPC testing was started on February 16, 2012. Table 6 - CEPC Pilot Test Summary, Phase 1 Parameter Baseline (no CEPC) CEPC Increase (decrease) Pilot testing start date Dec 15, 2009 Dec 21, 2010 Pilot testing end date April 30, 2010 April 26, 2011 Optimum FeC1 dose, mg /L none 30 Polymer dose, mg /L 1.25 Primary Clarifier TSS removal, percent 52.5 79.5 27 Primary Clarifier BOD removal, percent 45.6 70.4 25-30 Aeration Basin BOD Loading, ppd 2,880 1,930 (33) DESIGN CRITERIA FOR CHEMICAL COAGULANTS ADDED TO PRIMARY CLARIFIERS Addition of chemical coagulants to primary clarifiers has recently been included in the most recent draft of the Colorado Design Criteria for Domestic Wastewater Treatment Works (Colorado Department of Public Health and Environment, March 2012). The design criteria require that pilot plant testing with chemical coagulants be conducted to determine acceptable primary clarifier surface overflow rates or be based on results of similar full scale applications. The Avon WWTP conducted pilot testing and full scale testing of addition of chemical coagulants to the Avon primary clarifiers during 2010, 2011 and 2012. Therefore, the Avon CEPC improvements will be in compliance with the new Colorado Design Criteria when they are adopted later in 2012. PROPOSED FULL SCALE CEPC FACILITIES The recommended FeC13 dose for CEPC at Avon WWTP is 17 mg /L. FeC13 storage tanks will be double - walled high density cross - linked polyethylene construction. Each FeC13 storage tank will contain 1,550 gallons for a total of 3,100 gallon storage capacity at 38 percent FeC1 concentration. At the recommended 17 mg/L FeC1 dose (24 gallons per day) and average influent now of approximately 2.4 mgd, the proposed 3,100 gallons of chemical storage would provide a 129 day supply of ferric chloride. The shelf life of 38 percent ferric chloride is over 12 months when stored inside. i Dewberry May 2, 2012 Page 12 of 17 Ferric chloride is corrosive, non flammable, has a health hazard of 3 and reactivity of 2. Ferric chloride is a hazardous material under International Building Code (IBC). The amount stored that is exempt from code requirements in a closed system is 500 gallons with an increase to 1,000 gallons if in approved containers and room. Storage tanks for FeC1 will be located in an old chlorine storage room which is no longer needed since chlorine disinfection has been replaced by UV disinfection. Storage volume of 3,100 gallons of FeC1 will require an H4 occupancy per the 2009 IBC. The chemical storage room will need fire separation walls from adjacent areas and require anew fire sprinkler system. The existing concrete floor has a drain to the existing abandoned chlorine contact basin below. Ferric chloride that drains to the existing abandoned chlorine contact basin can be pumped to the headworks. FERRIC CHLORIDE FOR ODOR INCIDENT RESPONSE ERWSD currently intends to operate the CEPC metering facilities seasonally during the peak ski season and summer tourist season only. The Town could derive some additional odor control benefit if the CEPC system were also operated as a rapid response to odor incidents at the Avon WWTP. By metering ferric chloride or ferric sulfate into the primary clarifiers when an odor incident occurs, the release of odorous sulfur compounds into the air could be reduced significantly, probably within a few hours of starting the chemical addition. The CEPC system could provide an additional response method to terminate odor incidents relatively quickly when the root cause of the incident might take longer time to correct. Ferric chloride has been used for odor control in many wastewater collection systems and WWTPS. The Littleton - Englewood WWTP located in the Denver metropolitan area has successfully operated a ferric chloride metering system for many years to prevent odors at the primary clarifiers. The Southgate Sanitation District which is also located in the south Denver metropolitan area has a chemical metering station to control odors from the main interceptor sewers. The Southgate chemical metering station used ferric chloride for several years to control interceptor odors. CEPC EXPERIENCE AT OTHER WWTPS CEPC has been used for decades at many WWTPS worldwide. Representative full scale CEPC facilities are listed in Table 7. European development of CEPC technology started in the early 1970s mainly in Scandinavia to control algal blooms by reducing phosphorus in the effluent. More than two dozen WWTPS in Norway had implemented CEPC by the 1990s. The Metro Wastewater Reclamation District in Denver, Colorado has also used CEPC as an interim upgrade while constructing other improvements. �F Dewberry May 2, 2012 Page 13 of 17 Table 7 — Representative Full Scale CEPC Facilities Facility Location Capacity, m d CEPC coa ulant Point Loma WWTP San Diego, CA 240 iron salts Hyperion WWTP Los Angeles, CA 350 FeC1 Sutton Wastewater Reclamation Facility Cobb County, GA 60 FeC1 Deer Island WWTP Boston, MA 365 FeC1 Columbia Boulevard WWTP Portland, OR 300 FeC1 Greater Nanaimo Pollution Control Centre British Columbia, Canada 29 FeC1 Stonecutters Island Sewage Treatment Works Hong Kong, China 370 FeC1 DISCHARGE PERMIT COMPLIANCE SCHEDULES The current discharge permit for the Avon WWTP includes the compliance schedules summarized in Table 8. The compliance schedules are related to temperature monitoring in the Eagle River, Mixing Zone Study, TIN and arsenic discharge limits, and construction progress reports. None of these items are expected to affect the proposed CEPC improvements. Tahip R . Avnn WWTP niccharna Parmif r'mmnlinnra Gharhd Code Event Description Due Date 04301 Install Temperature Certify continuous temperature monitoring equipment is 4/30/2011 Meters installed and operational. 50008 Submit Mixing Collect and analyze site- specific data to determine if the 1/1/2012, Zone Study Results facility qualifies for Mixing Zone Exclusion. If a low flow 1/1/2013 condition is not reached on the receiving water during the first year, submit study results the following year. CS011 Activities to Meet Submit a report summarizing the results of the nitrogen 1/31/2012, TIN.and Total study on the Eagle River. Also submit information on the 1/31/2013, Recoverable possible sources of arsenic and activities taken to 1/31/2014 Arsenic limits reduce or eliminate these sources. CS010 Status /Progress Report progress in selecting an alternative to meet final 1/31/2015 p ermit limitations. CS016 Complete On -Site Complete construction of facilities or other appropriate 12/31/2015 Construction I actions to meet final discharge limitations. CONCLUSIONS Solids stabilization in the ATAD process was identified as a capacity limiting process at the Avon WWTP (Capacity Evaluation and Re- Rating Study, CH2M HILL, March 30, 2010). To achieve Class A biosolids consistently, the hydraulic capacity of the existing Avon ATAD system will be de -rated and the system will be base loaded with primary sludge at a constant feed rate up to the de -rated capacity. All excess waste solids, both primary sludge and waste activated sludge (WAS), from the Vail and Avon WWTPs will be discharged into the sewer to the Edwards WWTP. Base loading the existing Avon ATAD system mainly with primary sludge will improve performance of this ATAD system and reduce potential to generate odors. 111 Dewberry May 2, 2012 Page 14 of 17 Since the original pumped venturi aeration system was replaced with a jet mixing system, the modified Avon ATAD reactors are expected to maintain the dissolved oxygen control set point and therefore to have reduced potential to generate odors. The proposed CEPC system will maximize removal of suspended solids in the primary clarifiers. When the CEPC system is operating, the quantity of primary sludge will increase and the quantity of secondary WAS will decrease. Because all excess primary sludge and WAS will be discharged into the sewer to the Edwards WWTP, operation of the proposed CEPC system will not increase the solids loading to the existing Avon ATAD system (which will be base loaded with primary sludge). Operation of the proposed CEPC system will reduce the release of odor compounds from the ATAD reactors and reduce hydrogen sulfide corrosion. Implementing CEPC would reduce odor and corrosion potential in the primary clarifiers, ATAD reactors, and biosolids dewatering building. The Avon WWTP has a number of odor control systems which have proven capability to treat exhaust air odors effectively. The proposed CEPC system will reduce odor generation in the primary clarifiers, ATAD reactors, and biosolids dewatering building whenever the CEPC chemical metering system is operating. The existing odor control systems are expected to achieve equal or better performance after implementing CEPC than previously. The proposed CEPC system will maximize TSS and BOD5 capture efficiency in the primary clarifiers which will significantly reduce the organic and solids loading on the existing activated sludge treatment process. The reduced loading applied to the secondary treatment process will effectively increase nitrification capacity in the existing activated sludge process by maintaining a sufficient operating SRT to maintain the nitrifying biomass. The existing Avon WWTP has sufficient process equipment capacity to thicken WAS and dewater biosolids that will be produced by the Avon ATAD reactors. The recently upgraded Edwards WWTP has sufficient ATAD reactor capacity and thickening and dewatering capacity to accept all of the anticipated waste solids from the Vail and Avon WWTPs. Operation of the proposed CEPC system at the recommended FeC1 dose would require less than 6 truck loads of FeC1 chemical per year, even if operated continuously. The minimal number of chemical truck deliveries will have no appreciable effect on noise at the Avon WWTP or on traffic through the Town. Based on the evaluation of the benefits and potential impacts of the proposed CEPC system, approval of the Avon WWTP 1041 Permit Application is recommended. Dewberry May 2, 2012 Page 15 of 17 ACRONYMS AND ABBREVIATIONS ATAD Autothermal Thermophilic Aerobic Digestion BCF Biosolids Composting Facility BOD Biological oxygen demand at standard five day test conditions CDPHE Colorado Department of Public Health and Environment CDPS Colorado Discharge Permit System CEPC Chemically Enhanced Primary Clarification DO dissolved oxygen ERWSD Eagle River Water and Sanitation District GBT gravity belt thickeners gpd gallons per day IBC International Building Code IMLR internal mixed - liquor recirculation mgd million gallons per day mg /L milligrams per liter MLE Modified Ludzack- Ettinger process NWCCOG Northwest Colorado Council of Governments ORP oxidation - reduction potential ppd pounds per day RDT rotary drum thickener SCADA supervisory control and data acquisition SRT solids residence time TDS total dissolved solids TIN total inorganic nitrogen TSS total suspended solids UV ultraviolet WAS waste activated sludge WWTP wastewater treatment plant Dewberry �a;e� May 2, 2012 Page 16 of 17 REFERENCES Chagnon, F. and Harleman, D. R. F. (2001) An Introduction to Chemically Enhanced Primary Treatment, Massachusetts Institute of Technology, Cambridge, Massachusetts. CH2M HILL (March 2012) 1041 Permit Application for Avon WWTP CEPC Project, Englewood, Colorado. C112M HILL (March 2012) Site Application for Avon WWTP, Regulation 22, Englewood, Colorado. CH2M HILL (March 7, 2012) Avon Wastewater Treatment Plant 30% Design of Ferric Chloride Storage Facilities, Basis of Design Technical Memorandum, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (May 27, 2011) Chemically Enhanced Primary Clarification Pilot Study Results, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (March 30, 2010) Avon Wastewater Treatment Plant Capacity Evaluation and Re- Rating Study, report prepared for Eagle River Water and Sanitation District, Englewood, Colorado.. CH2M HILL (January 2010) Avon WWTP Chemically Enhanced Primary Clarification Project Drawings, prepared for Eagle River Water and Sanitation District, Englewood, Colorado. CH2M HILL (November 2009) Avon Wastewater Treatment Plant Chemically Enhanced Primary Clarification (CEPC) Project - Final Design Report, prepared for Eagle River Water and Sanitation District, Englewood, Colorado. Colorado Department of Public Health and Environment (April 29, 2011) CDPS Permit Number CO- 0024431 for Avon WWTP, amended, expiration date January 31, 2016, issued by Janet Kieler, Permits Section Manager, Water Quality Control Division, Denver, Colorado. Colorado Department of Public Health and Environment (March 19, 2012) State of Colorado Design Criteria For Domestic Wastewater Treatment Works, WPC -DR -1- Draft for Review, Water Quality Control Division, Denver, Colorado. Frachetti Engineering (February 2012) Process Design Report Avon Wastewater Treatment Facility, Secondary Treatment Improvements Project, prepared for Eagle River Water and Sanitation District, Greenwood Village, Colorado. Integra Engineering (April 22, 1997) Avon WWTP Odor Emissions Characterization, report prepared for Eagle River Water and Sanitation District, Denver, Colorado. OF I Dewberry May 2, 2012 Page 17 of 17 Kennedy -Jenks Consultants, Engineers and Scientists (January 28, 2010) 2008 Wastewater Master Plan Update, report prepared for Eagle River Water and Sanitation District, Lakewood, Colorado. Massachusetts Water Resources Authority (April 13, 2012) Renewable and Sustainable Energy Initiatives at Deer Island, httv://www.mwra.com/03sewer/htiiil/renewableenergydi.htm Boston, Massachusetts. Mills, Jeffrey A., Reardon, R. D., Chastain, C. E., Cameron, J. L., and Goodman, G. V. (October 2006) Chemically Enhanced Primary Treatment For a Large Water Reclamation Facility on a Constricted Site - Considerations for Design, Start -Up, and Operation, presented at the 2006 Water Environment Federation Annual Conference, Atlanta, Georgia. Parker, Denny S., Barnard, J., Daigger, G. T., Tekippe, R. J., and Wahlberg, E. J. (March 15, 2001) The Future of Chemically Enhanced Primary Treatment: Evolution Not Revolution, published by the International Water Association. Northwest Colorado Council of Governments (2002) 2002 Eagle River Water Quality Management Plan, Silverthome, Colorado. Stan Bernstein and Associates, Inc. (October 5, 2011) Sewer Operations — Multi year Financial Model, report prepared for Eagle River Water and Sanitation District, Greenwood Village, Colorado. Town of Avon (2012) Avon Municipal Code, Chapter 7.40, 1041 Regulations, Avon, Colorado. USEPA (October 19, 2007) General Permit Number COG - 650000 for Sewage Sludge, issued by Regional Biosolids Program, USEPA Region 8, Denver, Colorado. Dewberry Exhibit C TOWN OF AVON, COLORADO ORDINANCE 12 -06 SERIES OF 2012 AN ORDINANCE APPROVING A PERMIT FOR AREAS AND ACTIVITIES OF STATE AND LOCAL INTEREST (1041 PERMIT) FOR THE EAGLE RIVER WATER AND SANITATION DISTRICT FOR AN EXPANSION OF THE AVON WASTEWATER TREATMENT PLANT WHEREAS, the Town of Avon ( "Town ") is a home rule authority municipal corporation and body politic organized under the laws of the State of Colorado and possessing the maximum powers, authority and privileges to which it is entitled under Colorado law; and WHEREAS, Chapter 7.40 of the Avon Municipal Code authorizes the Town to review permit requests for areas and activities of state and local interest (1041 Permits); and WHEREAS, Eagle River Water and Sanitation District ( "the Owner ") has submitted an application for a 1041 Permit to expand the Avon Wastewater Treatment Plant; and WHEREAS, pursuant to Section 7.40.660, Approval of permit application, Avon Municipal Code, the Town Council has considered the applicable review criteria; and WHEREAS, the Town Council held public hearings on May 22, 2012 and June 12, 2012 after posting notice of such hearing in accordance with the requirements of Section 7.40.250, Public notice requirements, Avon Municipal Code, and considered all comments provided before taking action; and WHEREAS, it is the Town Council's opinion that the health, safety and welfare of the citizens of the Town of Avon would be enhanced and promoted by the adoption of this ordinance; and WHEREAS, approval of this Ordinance on first reading is intended only to confirm that the Town Council desires to comply with the requirements of the Avon Home Rule Charter by setting a public hearing in order to provide the public an opportunity to present testimony and evidence regarding the application and that approval of this Ordinance on first reading does not constitute a representation that the Town Council, or any member of the Town Council, supports, approves, rejects, or denies this ordinance; NOW THEREFORE, BE IT ORDAINED BY THE TOWN COUNCIL OF THE TOWN OF AVON, COLORADO, the following: Section 1 Recitals Incorporated The above and foregoing recitals are incorporated herein by reference and adopted as findings and determinations of the Town Council. Ord 12- 061041 Permit for Avon WWTP Expansion May 22, 2012 First Reading revision Page 1 of 3 Section 2 Approval of a 1041 Permit The 1041 Permit for the expansion of the Avon Wastewater Treatment Plant as outlined in the Staff Memorandum dated May 22, 2012 is hereby approved with the following conditions: 1. In addition to its use during peak seasonal periods as determined by the Eagle River Water and Sanitation District, the Chemically Enhanced Primary Clarification system will also be operated as a rapid response to odor incidents at the Avon Wastewater Treatment Plant. Section 3 Severability If any provision of this Ordinance, or the application of such provision to any person or circumstance, is for any reason held to be invalid, such invalidity shall not affect other provisions or applications of this Ordinance which can be given effect without the invalid provision or application, and to this end the provisions of this Ordinance are declared to be severable. The Town Council hereby declares that it would have passed this Ordinance and each provision thereof, even though any one of the provisions might be declared unconstitutional or invalid. As used in this Section, the term "provision" means and includes any part, division, subdivision, section, subsection, sentence, clause or phrase; the term "application" means and includes an application of an ordinance or any part thereof, whether considered or construed alone or together with another ordinance or ordinances, or part thereof, of the Town. Section 4 Effective Date This Ordinance shall take effect thirty days after final adoption in accordance with Section 6.4 of the Avon Home Rule Charter. Section 5 Safety Clause The Town Council hereby finds, determines and declares that this Ordinance is promulgated under the general police power of the Town of Avon, that it is promulgated for the health, safety and welfare of the public, and that this Ordinance is necessary for the preservation of health and safety and for the protection of public convenience and welfare. The Town Council further determines that the Ordinance bears a rational relation to the proper legislative object sought to be obtained. Section 6 No Existing Violation Affected Nothing in this Ordinance shall be construed to release, extinguish, alter, modify, or change in whole or in part any penalty, liability or right or affect any audit, suit, or proceeding pending in any court, or any rights acquired, or liability incurred, or any cause or causes of action acquired or existing which may have been incurred or obtained under any ordinance or provision hereby repealed or amended by this Ordinance. Any such ordinance or provision thereof so amended, repealed, or superseded by this Ordinance shall be treated and held as remaining in force for the purpose of sustaining any and all proper actions, suits, proceedings and prosecutions, for the enforcement of such penalty, liability, or right, and for the purpose of sustaining any judgment, decree or order which can or may be rendered, entered, or made in such actions, suits or proceedings, or prosecutions imposing, inflicting, or declaring such penalty or liability or enforcing such right, and shall be treated and held as remaining in force for the purpose of sustaining any and all proceedings, actions, hearings, and appeals pending before any court or administrative tribunal. Ord 12 -06 1041 Permit for Avon W WTP Expansion May 22, 2012 First Reading revision Page 2 of 3 Section 7. Publication by Posting The Town Clerk is ordered to publish this Ordinance by posting notice of adoption of this Ordinance on final reading by title in at least three public places within the Town and posting at the office of the Town Clerk, which notice shall contain a statement that a copy of the ordinance in full is available for public inspection in the office of the Town Clerk during normal business hours. INTRODUCED, APPROVED, PASSED ON FIRST READING, ORDERED POSTED AND REFERRED TO PUBLIC HEARING and setting such public hearing for 5:30 on June 12, 2012 at the Council Chambers of the Avon Municipal Building, located at One Lake Street, Avon, Colorado, on May 22, 2012. Rich Carroll, Mayor Published by posting in at least three public places in Town and posting at the office of the Town Clerk at least seven days prior to final action by the Town Council. ATTEST: APPROVED AS TO FORM: Patty McKenny, Town Clerk Eric Heil, Town Attorney INTRODUCED, FINALLY APPROVED, AND PASSED ON SECOND READING, AND ORDERED PUBLISHED BY POSTING on June 12, 2012. Rich Carroll, Mayor Published by posting by title in at least three public places in Town and posting by title at the office of the Town Clerk. ATTEST: Patty McKenny, Town Clerk Ord 12 -06 1041 Permit for Avon WWTP Expansion May 22, 2012 First Reading revision Page 3 of 3