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HomeMy WebLinkAboutNC0063096_Engineering Alternatives Analysis_20110812IV600( 30t Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion Engineering Alternatives Analysis dMP Tru: TOwn OF Holly Springs CAROI.INA Richard G. "Dick" Sears, Mayor James Cobb Tim Sack Chet VanFossen Linda Hunt Williams Parrish "Ham" Womble August,2011 DAVIS -MARTIN -POWELL & ASSOCIATES ENGINEERING • LAND PLANNING -SURVEYING 6415 Old Plank Road, High Point, NC 27265 (336)886-4821 1 Fax (336)886-4458 1 w .drop-inc.com CAROUNA 3040 NC 42 West, Clayton, NC 27520 ECOSYSTEMs_ Imc (919) 606-1065 1 Fax(919) 341-4474 Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion Engineering Alternatives Analysis Responsible Agency: Department of Environment & Natural Resources Division of Water Quality — Planning Section 1617 Mail Service Center Raleigh, NC 27699 Consultants Hannah Stallings, SEPA Coordinator (919) 807-6434 han nah.stallings(o) ncden r.0 ov Davis -Martin -Powell & Associates, Inc. 6415 Old Plank Road High Point, NC 27265 NC Firm F-0245 Michael L. Slusher, PE (336) 886-4821 MSIu sher(&dm p-inc.com Carolina Ecosystems, Inc. 3040 NC 42 West Clayton, NC 27520 Phil May (919) 606-1065 Phil. May(cDcarolinaeco. com Owner: Town of Holly Springs 128 South Main Street PO Box 8 Holly Springs, NC 27540 Stephanie L. Sudano, PE (919)557-3938 stephanie.sudano(a)hollvspringsnc. us TABLE OF CONTENTS Section Page Contents Table of Contents Abbreviations and Acronyms...................................................................................................... iv i. Project Summary .............................................................................................................1 i.1 Introduction..........................................................................................................1 i.2 Background..........................................................................................................2 0 Western Wake Regional Wastewater Management Facilities ..............................3 i.4 Purpose and Need...............................................................................................5 Section 1.0 - Population Projections, Design Flows and Wastewater Characteristics ..................7 1.1 Population Projections.........................................................................................7 1.2 Current Population...............................................................................................7 1.3 Existing Land Uses............................................................................................14 1.4 Flow Projections................................................................................................17 1.6 Influent Wastewater Characteristics...................................................................19 1.7 Existing Wastewater Treatment Facility.............................................................19 1.7.1 Treatment Process Overview.................................................................19 1.7.2 Biosolids Management...........................................................................21 1.7.3 Reclaimed Water Production..................................................................22 1.7.4 Treatment Performance..........................................................................23 Section 2.0 - Evaluation of Alternatives.....................................................................................31 2.1 General..............................................................................................................31 2.1.1 Management Option A: "No Action..........................................................31 2.1.2 Management Option B: Optimum Operation of Existing Facilities .......... 32 2.1.3 Management Option C: Harnett County Regional Interconnection ......... 32 2.1.4 Management Option D: Treatment at the Western Wake Regional WRF33 2.1.5 Management Option E: UCWRF Expansion and Discharge Relocation..34 2.2 Treatment Process Upgrades............................................................................34 2.2.1 Disc Filters Upgrade...............................................................................35 2.2.2 Deep Bed Denitrification Filters..............................................................36 2.2.3 Supplemental Carbon Feed System.......................................................36 2.2.4 Coagulant Feed System.........................................................................37 Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 6/1SQ01111:34:00 AM Hdly songs Fin W 10 2011.0 4 2.2.5 Biosolids Handling Upgrades..................................................................38 2.2.6 Present Worth Cost Estimate.................................................................39 2.3 Alternative 1: Cape Fear River Discharge.........................................................41 2.3.1 Background............................................................................................41 2.3.2 New Infrastructure..................................................................................42 2.4 Alternative 2: Harris Lake Watershed Discharge...............................................53 2.4.1 Background............................................................................................53 2.4.2 Holly Springs Speculative Limits.............................................................54 2.4.3 New Infrastructure..................................................................................56 2.5 Alternative E-3: Land Application.......................................................................63 2.6 Alternative E-4: Wastewater Reuse....................................................................69 2.7 Alternatives Evaluation & Summary ...................................................................73 Section3.0 - References...........................................................................................................75 APPENDICES Appendix A.....................................................................................NPDES Permit Appendix B................................... Correspondence with Division of Water Quality Appendix C...................................................................... Supplemental Cost Data Appendix D................................................................... Water Quality Information LIST OF TABLES Table..........................................................................................................Page 1-1 Population Trends.................................................................................... 7 1-2 Wastewater Flow Projections.................................................................18 1-3 Influent Wastewater Characteristics.......................................................19 1-4 2008-2010 Average Effluent Data..........................................................27 1-5 Effluent from Expanded UCWRF........................................................... 27 2-1 Chemical Phosphorus Precipitation....................................................... 38 2-2 Cape Fear Discharge Limits................................................................... 42 2-3 Cape Fear River, Present Worth Cost Estimates ................................... 44 2-4 Potential Environmental Impact............................................................. 45 2-5 Harris Lake Watershed Discharge Limits ............................................... 56 2-6 Potential Environmental Impact............................................................. 58 Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 811=011 8:12:00 AM Holly Sp ings EAA—Final 08 10 2011.docx 2-7 Lower Utley Creek, Present Worth Cost Estimates ................................ 58 2-8 Land Application, Present Worth Cost Estimates ................................... 65 2-9 Present Worth Cost Summary ................................................................ 73 2-10 Alternatives Summary ............................................................................ 74 LIST OF FIGURES Figure........................................................................................................ Page* i-1 Location Map...........................................................................................1 1-1 Planning and Service Area....................................................................... 9 1-2 Capital Improvement Projects................................................................11 1-3 Population Projections...........................................................................13 1-4 Land Use Plan.......................................................................................15 1-5 Flow Projections....................................................................................18 1-6 .............. UCWRF Existing Facilities Site Plan ...................................................... 25 1-7 Effluent Flow Trends.............................................................................. 28 1-8 Effluent TN & TP Trends........................................................................ 29 1-9 Effluent BOD & TSS Trends................................................................... 30 2-1 Alternative E-1: Cape Fear Discharge, Proposed Forcemain Route....... 47 2-2 Alternative E-1: Cape Fear Discharge, Overall Layout ........................... 49 2-3 Alternative E-1: Utley Creek WRF Upgraded Site Plan .......................... 51 2-4 Alternative E-2: Lower Utley Discharge, Proposed Outfall Route ........... 59 2-5 Alternative E-2: Utley Creek WRF Upgraded Site Plan .......................... 61 2-6 Alternative E-3: Land Application, Potential Sites ................................... 67 2-7 Alternative E-4: Reclaimed Water Service Area .................................... 71 *Figures are on or following the designated page. Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 8111520118:12:00 AM Holly Springs EAA _Final 08 10 2011.docx 4 ABBREVIATIONS AND ACRONYMS 201 Plan 201 Facilities Plan Amendment, specifically the Holly Springs Plan Amendment, prepared in 2006 by Davis -Martin -Powell and Green Engineering CG&L NCDENR DWQ Construction Grants & Loans Section DWQ NCDENR Division of Water Quality EA Environmental Assessment EAA Engineering Alternatives Analysis EIS, FEIS Environmental Impact Statement, specifically for the Western Wake Regional Wastewater Management Facilities ER, PER Preliminary Engineering Report NCDENR North Carolina Department of Environment and Natural Resources NEPA National Environmental Policy Act NPDES National Pollutant Discharge Elimination System permit program, specifically permits issued to Holly Springs and Western Wake Partners ROD Record of Decision, specifically for the Western Wake Regional Wastewater Management Facilities SEPA State Environmental Policy Act Town Town of Holly Springs UCWRF Utley Creek Water Reclamation Facility USACE US Army Corps of Engineers WRF, WWTP Water Reclamation Facility (Wastewater Treatment Plant) Western Wake Partners, Western Wake Regional Wastewater Management Facilities Partners Project Partners, an organization comprised of the Towns of Cary, Apex, Morrisville, and Holly Springs WWRWRF Western Wake Regional Water Reclamation Facility, specifically referring to the treatment plant and/or site Town of Holly Springs iv Wastewater Discharge Alternatives Evaluation & Expansion 8/15M011 s:12:00AM Holly Spdngs Era —Final 08 I0 2oltdxx I. PROJECT SUMMARY i.1 Introduction Davis -Martin -Powell and Associates was retained by the Town of Holly Springs, NC to prepare an Engineering Alternatives Analysis (EAA) addressing wastewater treatment system improvements at the Utley Creek Water Reclamation Facility (UCWRF) to determine the most practicable discharge system. Preparation of this document was recommended in a February 2010 Speculative Limits letter from the Division of Water Quality in response to the Town's request for speculative limits for discharge into Harris Lake. The Town of Holly Springs is a growing community located just south of the Research Triangle Park (18 miles) and Raleigh -Durham International Airport (23 miles) in western Wake County (Figure i-1). Holly Springs is bordered on the north by the Extra Territorial Jurisdiction (ETJ) area of Apex; on the east by the Cary ETJ; on the south by the Fuquay-Varina ETJ; and on the west by property owned by Progress Energy. There is a large amount of land both southwest and northwest of Holly Springs' town limits that does not currently lie within any corporate limits. Figure i-1 Town of Holly Springs Wastewater Discharge Alternatives Evaluation 8 Expansion 811&2011 8:12:00 AM Hdly Spdrgs EAA _ iml 08_10 2011.d= 1.2 Background The UCWRF serves the Town of Holly Springs and surrounding areas, and is located in Wake County, North Carolina. The UCWRF is currently permitted to discharge a monthly average wastewater flow rate of up to 2.4 million gallons per day (mgd) into Utley Creek, a tributary to Harris Lake, in the Cape Fear River Basin. The UCWRF was first constructed in the late 1980's with a capacity of 0.25 mgd, and quickly expanded to 0.5 mgd in 1994. With rapid growth occurring, the Town initiated a 201 Amendment in 1997 which led to the UCWRF expansion to 1.5 mgd in 1999. During this process DWQ expressed concerns about impacts on Utley Creek especially Thomas Mill Pond and Harris Lake. In March 2003 Holly Springs was issued an Utley Creek NPDES permit for 2.4 mgd, with the condition that the Town would investigate a regional solution for increased flows. The Town of Holly Springs then contracted with Davis -Martin -Powell and Green Engineering in 2004 to prepare another 201 Facilities Plan Amendment (hereafter referred to as "201 Plan") to evaluate wastewater treatment options to meet the Town's growing needs. Based on the flow projections, the Town would need 6.0 mgd (monthly average) treatment capacity for the 2030 planning period. The 201 Plan analyzed the following alternatives to provide wastewater treatment capacity: • Land Application • Expansion of the UCWRF to 2.4 mgd and transfer of 3.6 mgd to Harnett County North Regional VWIITP at Lillington • Expansion of the UCWRF to 2.4 mgd and transfer of 3.6 mgd to the Western Wake Regional WRF for treatment • Wastewater Reuse System • Expansion of the UCWRF to 6.0 mgd & convey treated effluent to Cape Fear River with Western Wake Partners The 201 Plan was approved in fall 2006 and recommended the expansion of the UCWRF to meet the Town's wastewater needs through 2025. NCDWQ issued a FONSI for this treatment facility expansion in February 2007 with language stating that future permits for, or authorizations to construct, the UCWRF would contain a condition that the Town would convey treated effluent to Town of Holly Springs 2 Wastewater Discharge Alternatives Evaluation & Expansion 8115MOl l 8:12:00 AM Holly Springs F.AA —Final 08_10 2011.doac 9 the Cape Fear River with the Western Wake Partners, when that system was available. A copy of this FONSI is included in Appendix B. The Town's UCWRF Upgrade and Expansion project proceeded into final design, which was approved and construction contracts awarded in fall 2007. Construction started in January 2008 and much of the new biological treatment process was placed into service in August 2009. The overall project was substantially completed in summer 2010. 1.3 Western Wake Regional Wastewater Management Facilities As early as 2002, six Wake County local governments (including Holly Springs) began working together to evaluate options for providing long-term wastewater management services for western Wake County. The Western Wake Partners, comprised of four local governments (including Apex, Cary, Morrisville and Holly Springs) proceeded with planning for regional wastewater treatment facilities to serve wastewater needs of western Wake County through the year 2030. The Western Wake Partners and US Army Corps of Engineers (USACE) developed an Environmental Impact Statement, which was finalized in 2009, with a Record of Decision (ROD) issued in July 2010 supporting the implementation of the project. The Town of Holly Springs has participated in the Western Wake Project as a result of DWQ's preference for regional cooperation, as stated in the 2007 FONSI for the UCWRF expansion that "any Authorization to Construct or other necessary permits (orders, etc.) for expansion of the Utley Creek WWTP will include a condition stating that the treated effluent must be removed from Utley Creek by the date established in the Certificate authorizing the Towns of Cary, Apex, and Morrisville and Wake County to Increase Their Transfer of Water from the Haw River basin to the Neuse River basin under the Provisions of G.S. 143-215.221." As stated in the USACE ROD, NCDWQ has indicated that as long as the Western Wake Partners are complying with the requirements of the IBT certificate, the Town of Holly Springs will be deemed to be meeting the requirements in the FONSI and that no modification is required. (USACE ROD, 2010). Jointly, the Partners plan to build interceptors, force mains, and pump stations to convey raw wastewater to a new water reclamation facility, along with discharge facilities to convey the treated effluent to the Cape Fear River below Buckhorn Dam. Various alternatives and sites were considered which have included Holly Springs as a participant in only effluent discharge facilities. Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 8115@0118:12:00 AM Holly Springs EAA Final 08 10 2011.docx 3 A The Holly Springs 201 Plan (2006) recommendations included subsequent construction of an effluent conveyance system to the Western Wake Regional WRF (WWRWRF). Effluents from the WWWRF and UCWRF would be combined and then conveyed and discharged into the Cape Fear River. Speculative limits for this discharge point were issued for both facilities in December 2004, up to 30 mgd from WWRWRF and up to 8 mgd from Holly Springs (maximum month flows). The WWRWRF project experienced several delays, including the required preparation of an EIS which began in 2007 and culminated with the USACE ROD. As a result, the original 2011 completion date has been pushed back until at least December 2013. The estimated cost to Holly Springs increased significantly due to additional work, inflation, and other delays, with the next phase of construction (effluent pumping, forcemain, and the Partner's effluent conveyance) now estimated at $39 million. This option would bring the Town's total wastewater infrastructure improvement costs to $67 million. The overall economic turndown that began in 2008 and is continuing at this time has forced the Town to further evaluate expenditures on all capital and infrastructure projects. Holly Springs was a participant in only the effluent conveyance components of the Western Wake Partners project, and the design and capacity of the WWRWRF treatment facilities are independent of Holly Springs' effluent. When Holly Springs withdrew from the partnership, there was minimal impact to the overall schedule for the remaining partners, as the wastewater treatment plant site is the first contract to be let and the effluent conveyance construction beginning approximately 6 months later. Based on preliminary evaluations the effluent pumping station capacity would be reduced, and the effluent forcemain diameter might be reduced from 60" to 54" which would reduce the construction cost. There have also been several developments in the planning area and during the planning process which have opened new potential discharge alternatives for Holly Springs such as: • Progress Energy Carolinas announced plans to construct additional nuclear power reactors at its Shearon Harris Facility. To supply adequate cooling water for the new reactors, Harris Lake level will be expanded, and water must be pumped from the Cape Fear River to supplement the natural drainage areas. Holly Springs and/or Western Wake Partners effluent discharge into Harris Lake could in part replace water needed from the Cape Fear River. • The Western Wake Partners began an evaluation of a discharge into Harris Lake as an alternative to the costly Cape Fear effluent conveyance system. The Western Wake Partners commissioned Town of Holly Springs 4 Wastewater Discharge Alternatives Evaluation & Expansion 811&20118:12:00AM Maly Springs EAA—Final 08 10 2011.docx 0- water quality monitoring and water quality modeling to determine if both the WWRWRF and UCWRF effluents could be discharged into Harris Lake without impairing water quality. While this investigation may have shown Harris Lake was a practicable alternative discharge location; the additional regulatory approvals required for Cary and Apex IBT certificate could further delay the project by at least three years and more likely 5 years. The Partners, faced with a June 2014 deadline, determined they could not continue to delay the project, and Harris Lake was determined to not meet the purpose and need for the Western Wake WRF discharge. • Since Western Wake Partners evaluation demonstrated that Harris Lake could support the wastewater discharges, the Town of Holly Springs continued to pursue this option independently. Additional modeling was conducted to analyze a Holly Springs discharge into the White Oak Arm of Harris Lake, and presented to NCDENR-DWQ in December 2009 for review. In February2010, the Town of Holly Springs received speculative limits for a Harris Lake discharge of 6 and 8 mgd. • The Western Wake Partners' final Cape Fear River NPDES limits were more stringent than the 2005 speculative limits. These more restrictive limits include seasonal (April to October) mass limits based on permitted flow and a value of 3.5 mg/L for TN and 0.5 mg/L for TP. In addition, there is a monthly average concentration limit of 5.0 mg/L for TN and 0.75 mg/L for TP, also applicable from April to October. These changes will significantly affect the level of treatment required at the UCWRF. L4 Purpose and Need The purpose of this Engineering Alternatives Analysis (EAA) is to evaluate the various discharge alternatives available for the wastewater effluent generated from the Town's expanded treatment facilities. This is required with any NPDES application in accordance with 15A NCAC 21-1.0105(c)(2) as noted in the speculative limits letters. The 2007 FONSI has justified the project growth and wastewater flows for Holly Springs and the Western Wake FEIS and ROD were subsequently justified the 8 mgd. This EAA is limited to review of viable alternatives to a Cape Fear River discharge, and including management options of Optimum Operation, Land Application, and Wastewater Reuse. Connections to other systems (Regional Solutions) were evaluated in the 201 Plan and FEIS and since the UCWRF plant has been expanded, are revisited in this report. This report was prepared using the guidelines established in the "Engineering Alternatives Analysis (EAA) Guidance Document, North Carolina Division of Water Quality/ NPDES (June 23, 2005)" and the Construction Grants & Loans Division's "Guidance for the Preparation of Engineering Reports" (April 2005). Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 8115R011 8:12:00 AM Holly Springs EAA Final 08 10 2011.dacn 5 This Page Intentionally Blank Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly Springs EAA Final OS 10 2011.docx HollyAM :L'"sr..-.NORTHCAROLINA Town GiS Sewer Map �r �i .,� ,.r{am� 1- • rr� �'i�lT �'f.�i4 ■ -� r'•r.,s2 �r $.� n'-: r• a rA t % . a 1 4J r' VAR • �_ L •1• 1�4 M1�} i, SAY: w � •' � �.-.� i � . .R � 4 �. 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PlM1P STRTIOiO - ae 1 OCOiNa ■ . � PlmPmsed pumA Sta'bOdk4 %'� ��yy r iF "'-' y � �1'OpDIEd IIYILYIl1'Y �41fltQ �1i�i1� PROPOSED REGIONAL r '■ �' -11 TO" tYHb it PINYp+STATION . f ; Town ETJ Area �r li ~ Pfopmy Pamph, + _ i r • Ex WW P am Irc ' i IAIfhN SIYIMJI OuwLaw . i Pimp Fukim Half Lk Vftw Sultama 2eOFt Elevation y 7� •. \ j 1 NO Ll L o 1� PROP rRW MAL - . _ .4 P'I>aned Fol�lR S1i11Bdl Upl]nMlea � -. c. PUIItP STAnCM I � 1 FIGURE 1-2 � ` d ■ • _ i a"CnMI f ti OPO PRSED i�O�IAL PLNPSTAT M 80mW _ 0 RRO MAL P MOTES: u _ t ' - 1. "INTERIM" PUMP STATIONS, UPSTREAM FROM PLANNED y f M a- Y REGIONAL ONES, WILL CONTINUE TO BE NECESSARY AS Aj TEMPORARY STEPS TO SERVE UPPER REACHES OF DEVELOPMENT BASINS. W E f .. SluaamCt"k PROPOSED Z. NEW GRAVITY SEWER LINES WILL PROGRESS FROM UPPER PUMP START REACHES OF EACH BASIN TO LOWER AREAS OF BASIN AS S "INTERIM" PUMP STATIONS MOVE DOWNSTREAM. IN ADDITION, M NEW GRAVITY SEWER LINES WILL BE INSTALLED TO TAKE PUMP STATIONS OFF LINE. 0 2.600 5,200 - -- _ - - --- — - - - - Fed T i Sep$wnber 2010 Up" p • ' •gyp {ice: � ` �, - - f #Aw* wd imN5ol cAnh Ct TO pFbN $p+�TBMrwT=,:;VM=10 Y a , � • i ill/IfNrYlljm.prilrnt Mb�T19pWl�tlf b#*wik t R, Sacd oltfat iidetii ly M wr ix Meikvlas° 64W NC 27trrjCc+Ytli. TM rMrur aia9mr]if]i .Mw��s orn..No,n�waaar.�w+s OfftMb mak"Mbit"us&#&, This Page Intentionally Blank Town of Holly Springs 12 Wastewater Discharge Alternatives Evaluation & Expansion 8115)20118:12:00 AM Flolly Sprfngs EAA Final 08 10 2011.docx sum Tum sum sum ."m 3mm 2UM lum Figure 1-3 Population Projections mm SGm SGm mu 2M mn 2= Town of Holly Springs 13 Wastewater Discharge Alternatives Evaluation & Expansion WlSn011 8:12M M Hdlysptlngs EM_FireW102011.O 1 The Town of Holly Springs has undergone growth rates that are unlike those of the surrounding Wake County. While Wake County has experienced an annual population growth rate of about 4.3%, Holly Springs experienced a growth rate of 16.8% from 2000 to 2010 (US Census Bureau). Population projections were developed in 2006 and growth rates were estimated using the higher Town rate (10.4%, 2004 data) for the first ten years. This growth rate was projected to decline gradually from 2015 to 2020, then remain equal to the Wake County rate (2.7%, 2004) for the remainder of the planning period. These higher rate growth projections for the first 10 years are supported by preliminary development plans already approved by the Town and construction schedules anticipated by the developers. The growth rate was substantiated by the preliminary 2010 population numbers. The population projections for the Town of Holly Springs are presented in Figure 1-3. Town of Holly Springs 8 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly Springs EAA Final 08102011.docc SECTION 1.0 - POPULATION PROJECTIONS, DESIGN FLOWS AND WASTEWATER CHARACTERISTICS 1.1 Population Projections In order to evaluate wastewater facilities needs for a 20-year planning period, projections of population and wastewater flows were prepared. Historical population trends and projections from North Carolina State Demographics were reviewed. These projections included herein were developed jointly with Western Wake Partners during 2006 and have been approved in Holly Springs 201 Plan, Western Wake Partner's FEIS and Engineering Report, and the USACE ROD. 1.2 Current Population Census data indicates that the Town of Holly Springs was one of North Carolina's most rapidly growing municipalities between 1990 and 2000. Based on preliminary 2010 Census data, development continues at a greater rate than Wake County's overall average growth rate, as shown in Table 1-1. Table 1-1 Population Trends 908 9,192 912 % 24,661 1 Notes: ` Preliminary Census Data Based on these population figures, the population of Holly Springs increased approximately tenfold in a decade, due primarily to new home construction. According to 2000 Census data, there were 3,316 housing units in Holly Springs, yielding an average household consisting of 2.77 persons. The 2010 Census data has not been fully released at this time. The Town's existing sewer collection system is shown in Figure 1-1 and their proposed wastewater service area is depicted in Figure 1-2. Figure 1-2 also identifies major capital improvement projects (CIP). The other CIP projects shown on this figure are outside the scope of analysis of this report. Town of Holly Springs 7 Wastewater Discharge Alternatives Evaluation & Expansion 8115W 1 8.12:00 AM Holly Springs EAA _Final 08_10_2011 Eoc 1.3 Existing Land Uses The Town currently has zoning ordinances in place which include the following main categories and corresponding districts. o Residential: Single Family; Multifamily; High -Density Multifamily o Commercial/Mixed Use: Neighborhood Village; Local Business; Town Village; Office, Research, and Development Park; Community Business; General Business v Industrial: Warehouse/Distribution; Light Industrial; General Industrial Areas south and west of Holly Springs are experiencing more rapid residential growth. Commercial and industrial development is expected to dominate the north and west areas of Town. The proposed Wake County Outer Loop will intersect with the Holly Springs Bypass immediately north of Town and will likely support more commercial and industrial growth. The potential growth area west of Town extends to the property owned by Progress Energy. This area is logical for industrial development. Figure 1-4 on the following page shows the current Land Use Plan for the Town of Holly Springs and surrounding areas. Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 8115=11 8.1 ZOO AM Holly Springs EAA Jinal 0810 2011.docx 14 Future Land Use Plan Figure 1-4 F IE 175HIp RD .�1 11 Torn of Holy Springs 7.!�� �« "il���r��� J� This Page Intentionally Blank Town of Holly Springs 16 Wastewater Discharge Alternatives Evaluation & Expansion 811 SM01 18:12:00 AM Molly Springs EAA Final 08 10 2011.docn 1.4 Flow Projections Wastewater flow projections used the Holly Springs' service area to develop the capacity in the 201 Plan Upgrade & Expansion and are presented in the EAA document. These projections were developed cooperatively for the 201 Plan (2006) and the Western Wake SEPA EIS (CDM, Hazen and Sawyer, and CH2MHILL, 2005). They were closely coordinated with DWQ NPDES and CG&L staff to comply with program guidelines in effect at that time. The Town's 2006 FNSI ad Western Wake ROD were issued based on these projections. Wastewater flow projections were developed using information and data from water and sewer billing records, daily monitoring report (DMR) data, and future land use plans. After review and analysis of water and sewer billing records, DMR data, and future land use plans, the 2030 wastewater flow projection for the Town of Holly Springs was developed using the following methodology. o Year 2004 was used as the baseline for flow projections o The 2004 average daily flow was broken down using billing records into 0.851 mgd residential, 0.063 mgd Commercial, and 0.007 mgd Industrial o Population Projections from Section 1.2 were applied o Maximum month peak factor was determined from DMR data o Hydraulic peaking factor of 3.1 for effluent conveyance was used based on Western Wake agreements The results of the flow projection are presented in Table 1-2 and graphically in Figure 1-5. Town of Holly Springs 17 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly Springs EAA _Final 08 10 2011.doac Table 1-2: Wastewater Flow (mgd) Population 2005 15,090 2010 24,740 20152020 40,570 53,980 2025 62,290 2030 71,870 Residential 0.95 1.63 2.73 3.67 4.25 4.92 Commercial 0.08 0.23 0.47 0.67 0.79 0.94 Industrial 0.11 0.32 0.45 0.57 0.64 0.72 Net Average Daily Flow 1.15 2.17 3.65 4.91 5.68 6.58 Estimated 1/1141 0.32 0.32 0.32 0.32 0.32 0.32 Total Average Daily Flow 1.46 2.49 3.97 5.22 6.00 6.90 Maximum Month Flow 1.76 2.99 4.76 6.27 7.20 8.28 Peak Flow 4.54 7.72 12.31 16.20 18.60 21.38 9,000, 8,000, 7,coo, 6,000, a � 5,000, 3 0 u 4,000, 3,000, 2,000, 1,000, Notes: (1) 2004 flow plus 70 gpcd for growth population (2) 2004 flow plus 15 gpcd for growth population (3) Estimated at 10% of Residenfial & Commercial plus a committed flow of 0.125 mgd (4) Estimated at 0.32 mgd based on an 1/1 evaluation conducted for Holly Springs's service area and plans for 1/1 reduction (5) Average daily flow times 1.2 (Based on DMR data for fiscal year 2002-2003) (6) Average daily flow times 3.1 (Based on wastewater flow analysis for a portion of Western Wake service area. This peaking factor is included in the wastewater services interlocal agreement executed by the Project Partners). Figure 1-6: Flow Projections D00 D00 Do0 300 ■ Average Annual Flow • Maximum Month Flow 300 300 )00 )00 )00 0 2000 2005 2010 2015 2020 2025 2030 Town of Holly Springs 18 Wastewater Discharge Alternatives Evaluation & Expansion 8/1520118:12:00 AM Holly SpOgs EPA _FIre108_10_2011.d= 1.6 Influent Wastewater Characteristics UCWRF influent data for the period from January 2008 through December 2010 was reviewed in order to develop projected wastewater characteristics. This data, summarized in Table 1-4, was initially presented in the 201 Plan (2006) and served as the basis of design for the facility Upgrade and Expansion. Table 1-3 Influent Wastewater Characteristics Parameter Flow, mgd AverageAnnual 1.19 Maximum Month 1.66 BODE, mg/L 356 508 Total Suspended Solids, mg/L 412 659 Ammonia Nitrogen, mg/L 36 44 Nitrogen (TKN), mg/L 43 53 Total Phosphorus, mg/L 8 8.6 Note: TN & TP limited raw data 1.7 Existing Wastewater Treatment Facility The UCWRF is located on a 35 acre site just west of the Highway 55 Bypass. The current design capacity of the plant is 6.0 mgd average flow with a 15.0 mgd process peak flow. The 6.0 mgd Expansion and Upgrade project was substantially completed during summer 2010 and provides state of the art treatment, multiple process trains, and biological nutrient removal. An overview of plant processes follows and Figure 1-6 shows a site plan of the UCWRF as currently configured. 1.7.1 Treatment Process Overview Preliminary treatment includes an influent flow measurement; dual automatic self cleaning mechanical bar screens; manually cleaned bypass screen; dual vortex/gravity grit separators; and Town of Holly Springs 19 Wastewater Discharge Alternatives Evaluation & Expansion &1W0118'. 1ZW AM H61y5pnigs EAA _Final 08102011. Jo a grit concentrator. These components are capable of passing a peak flow of 20 mgd. An influent pump station consisting of six (6) variable speed submersible pumps is capable of delivering peak influent flows of 20.0 mgd and a maximum RAS flow of 10 mgd. The influent pump station is designed so that return sludge and the majority of the treatment basins can drain into it by gravity. Biological treatment is provided using the EIMCO Carrousel"m oxidation ditch process. The Town installed a single train oxidation ditch with an anoxic zone in 2000 during the 1.5 mgd upgrade and it had performed well even at high loading conditions. New modifications to the existing train include the construction of an anaerobic zone, and rating for 1.2 mgd through that train. In order to obtain the desired capacity, two (2) parallel 2.4 mgd activated sludge oxidation ditches were constructed including anaerobic and anoxic zones. These units will operate in parallel with the existing basin, with a new primary flow splitting structure dividing influent flow proportionally between the three trains. Dual train second anoxic zone and reaeration zone receive the combined aeration basin effluents and provide a complete five -stage BNR process to achieve maximum biological nitrogen and phosphorus reduction. Flow is evenly split between three 90 foot diameter, 16-foot deep, secondary clarifiers. A chemical feed system is provided to feed a coagulant to the clarifier inlet to provide for additional phosphorus removal. This chemical system is designed to use ferric chloride and alum based coagulants, and the UCWRF Staff has been using sodium aluminate with good results.. Return activated sludge (RAS) flows by gravity to a new RAS/WAS structure and sludge withdrawal rates are controlled by telescoping valves from each clarifier, metered, and then flows by gravity to the RAS Screening Building and then to the Influent Pump Station. Secondary Clarifier effluent is then treated by cloth media disc filters. Four parallel filter units are provided to handle peak flows with one unit out of service. Effluent is disinfected with a low pressure -high intensity ultraviolet system. The UV system is designed with two banks in a single channel, and was designed to meet the NPDES fecal coliform limits of 200/100ml- with one bank out of service. The channel length can accommodate Town of Holly Springs 20 Wastewater Discharge Alternatives Evaluation & Expansion 811&2011 8:12:00 AM Holly Springs EAA Final 08102011.doax a third bank to meet the reclaimed water standard of 14/100mL at peak flow rates up to 15 mgd. The current two bank configuration can meet the reclaimed standard at up to 7 mgd peak flows. The existing cascade aerator has been utilized for aeration of the effluent during the initial period when the effluent continues to discharge into Utley Creek. This component will be abandoned when the ultimate discharge system is constructed. The facility has two standby diesel generators to provide emergency power and a distributed SCADA control system. 1.7.2 Biosolids Management Historically, the UCWRF has relied upon aerobic digestion and land application of liquid sludge for ultimate disposal (a contracted service with Synagro). In recent years, timely disposal has become a concern, due to changes in permitted land and weather patterns which limit access to the fields. Plant Operators have been supplementing the aerobic digestion process with lime addition to meet Class B requirements, increasing disposal costs about 40%. Private composting facilities are also utilized to dispose of solids during wet conditions. The Town had been concerned about the long term viability of the land application program, as finding suitable land is increasingly difficult due to development and community concerns about land application of biosolids. Some recently acquired farmland has been up to 50 miles from the plant. Holly Springs, like many municipalities is developing a comprehensive biosolids management program with multiple disposal options. The Expansion & Upgrade project included the Siemens Cannibal® Solids Reduction Process. This is a relatively new process which utilizes physical and biological treatments to significantly reduce the volume of sludge which must be disposed. The Solids Reduction Process operates by continuously screening a portion of the RAS flow to remove non -biological material. This inert material is estimated to be 25-30% of typical waste sludge production. The screenings then are compacted and can be disposed of in a municipal solid waste landfill, similar to headworks screenings and grit. A cyclone separator is also used remove other inert materials from the RAS. This concentrated material is high in phosphorus and will be wasted directly to the digester. Town of Holly Springs 21 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12.00 AM Hotly Springs EAA _Final 08_10 2011.docx The process also biologically conditions a portion of the RAS using Interchange Tanks equipped with mixers and diffused aeration. The Interchange Tank has an anoxic environment to further biologically consume the microorganisms which are normally wasted on a daily basis. Normal operation of the Interchange Tank is to return conditioned RAS to the aeration basin once each day, then be refilled with fresh RAS. Construction of the second interchange tank would be delayed until construction of the effluent conveyance project when the existing cascade aerator is abandoned. The single 900,000 gallon interchange tank will be adequate until average flow exceeds 3 mgd. The process does require periodic solids wasting (or purges), which would be equivalent to a 0.30 sludge yield (pounds of sludge produced per pound of BOD removed). This is much less than the typical 0.7-1.0 yield anticipated from BNR sludge processes. Purging does not have to occur daily, but can be scheduled at various frequencies as needed to facilitate sludge disposal operations. Some plants using this process only purge quarterly or even annually. Decanters will be provided in all tanks to thicken the sludge. The existing clarifier was converted into an aerobic digester for treatment of the purged sludge. Based on the reduced sludge yield, this 0.46 MG basin provides adequate volume for aerobic digestion to produce a sludge meeting 503 regulations for vector and pathogen reduction. When needed, lime can also be added to accelerate the stabilization process. At full design capacity, the digester provides about 20 days holding capacity. The reduction in sludge volume will result in an immediate savings and extend the useful life of currently permitted land. McGill Environmental, a private composting facility, has also agreed to receive waste sludge from the Town when weather conditions prohibit timely land application. The Town also continues to pursue other sludge disposal alternatives. Potential options include sending digested liquid sludge to area facilities for thermal drying, dewatering sludge for offsite composting, and municipal landfill co -disposal. 1.7.3 Reclaimed Water Production Holly Springs' long-range water supply and wastewater management plans includes a commitment to promote utilization of reclaimed water. This was initiated in 2000 with the Town of Holly Springs 22 Wastewater Discharge Alternatives Evaluation & Expansion 8115=1 1 8:12:00AM Holly Springs EAA —Final 08 10 201l.docc "Wastewater Reuse Master Plan" and since 2007 the Town has completed a reclaimed pumping system, elevated storage tank, and a significant network of reclaimed distribution mains serving the western side of Town. Committed reclaimed usage is expected to average over 0.25 mgd (annual average) with season demands in excess of 0.75 mgd. Reclaimed water came online in June 2010 and demand from the initial customers has averaged 0.125 mgd. The reclaimed water quality relies on the effluent filters and UV, and also includes a hypochlorite system to maintain chlorine residuals in the distribution system to prevent formation of slimes and possible regrowth of bacteria. The reclaimed water pumps are located downstream of the UV disinfection and have a firm 1.5 mgd capacity. A 30" diameter pipe segment on the UCWRF site provides 30 minutes chlorine contact detention prior to reclaimed water utilization. The UCWRF will utilize reclaimed water for non -potable process water, onsite irrigation, and a bulk water distribution facility is also located on the site. See section 2.9 for further discussion of the Reclaimed Water System. 1.7.4 Treatment Performance Since the 2000 capacity expansion the UCWRF has consistently performed well. The Upgrade & Expansion project has improved effluent filtration and UV disinfection with new technologies for more reliable performance and redundancy. Most components of the expanded process train were placed into initial operation in August 2009 and results are excellent. There was short period during fall 2009 as the new biological process facilities were being started up and construction of ancillary components were not yet complete, when nutrient reduction was not being optimized. The Operators immediately begin to review the situation and optimize the treatment process, and effluent data from 2010 indicates the UCWRF is achieving the intended results. A summary of effluent data is provided in the following tables and graphs (Figures 1-7, 1-8, 1-9). Town of Holly Springs 23 Wastewater Discharge Alternatives Evaluation & Expansion 811=011 8:12:00 AM Holly Spdngs E4A _Final 08 10 2011.docx This Page Intentionally Blank Town of Holly Springs 24 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly Springs EAA_Fina! 08 10 2011.docx NN ANOXIC/ CLARIFIER 1 REAIR CLARIFIER CLARIFIER #2 #3 LIV FILT-ERS CHEM SCREEN BLDG. SHT 1 E-1 AB 3 AB 2 A13 I SLUDGE E ADMIN. BLDG. MAINT. BLDG. PS SLUDGE& RECLAIMED TRUCK LOADING IT il I IPS n \-_PROPERTY LINE IT BLOWERS - TOWN OF HOLLY SPRINGS ENGINEERING ALTERNATIVES ANALYSIS DISCHARGE ALTERNATIVES EVALUATION GRAPHIC SCALE 80 40 0 80 FIGURE 1-6 UTLEY CREEK WRIF EXISTING SITE PLAN This Page Intentionally Blank Town of Holly Springs 26 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/28118:12:Ob AM Holly Springs EAA _Final 08102011.docx Table 1-4 2008 - 2010 Average Effluent Data Flow, mgd 2008Parameter 1.00 rr 1.23 r 1.35 BODS, mg/L 1.9 7.2 1.0 TSS, mg/L 3.0 8.4 0.4 Ammonia, mg/I 0.21 1.24 0.38 Fecal Coliform, #/100mL 5 65 < 2 TN, mg/L 11.3 8.9 4.1 TKN, mg/L 6.9 1.9 0.8 NO2-NO3, mg/L 6.0 6.7 3.4 TP, mg/L 3.3 2.8 0.8 2009 during Upgrade & Expansion Construction . During Jan to April 2009 previous Effluent Filter system experienced mechanical problems 2010 data, also during plant startup Table 1-5 Effluent from Expanded UCWRF Flow, mgd May rr 1.44 June 2010 1.24 July 2010 1.38 Aug 2010 1.43 Sept 2010 1.31 OctParameter 2010 1.39 2010 1.33 Dec 2010 1.34 BODE, mg/L 2.8 <2 0.1 0.1 <2 <2 <2 2.8 TSS, mg/L <1 <1 0.2 0.2 <1 1.0 <1 1.0 Ammonia, mgll <0.5 <0.5 0.0 0.6 <0.5 2.0 <0.5 <0.5 Fecal Coliform, #1100 mL 1 1 1.86 1 <1 <1 <1 <1 TN, mg/L 3.26 2.65 4.06 4.76 3.68 1.98 2.01 2.18 TKN, mg/L 0.67 0.69 0.74 1.13 0.59 0.82 0.67 0.63 NO2-NO3, mg/L 2.65 2.36 3.32 3.70 3.18 1.16 1.34 1.54 TP, mg/L 0.30 1.75 1.51 0.19 0.20 <0.1 <0.1 0.10 Data from UCWRF DMR's Town of Holly Springs 27 Wastewater Discharge Alternatives Evaluation & Expansion Wl W0118:12A0 AM Hdly Springs EAA _Fir 08_10_2011.dm Figure 1-7 Effluent Flow Trends Flow 3.50 —90 per. Mov. Avg. I{10N) 3.00 ISO u 2.00 LL I kI 1.SO " 1.00 Iwo 0.50 0.00 g oo g o `8 ig �o 0 � � � � 0 0 0 N N N C�j po Ny po N N p0 p0 N Np N po fV N po N pc Np. N Qo N N N p0 N l jN{ O 7 jNj O jN� O jNf O jNf O l CL }sN( Q Q Q Q -Wi Q Q/ Town of Holly Springs 28 Wastewater Discharge Alternatives Evaluation & Expansion 8H520118:12:o0AM Holly Springs EAA_riml 08_10_2011. o Figure 1.8 Effluent TN & TP Trends 20.00 - -- • TP ■ TN 16.00 ----- 90 per. Mov. Avg. (TP) ■ ---- 90 per. Mov. Avg. (TN) ■ 12.00 �- E r - i)� ■ ■ o i ■ ■ ■ ■ ■ 8.00 J u° � ■ : ■■ ■ ■ ■ ■ ■ • ■�■■ �� j ■-r ■ ■ ri ■ �• • 44 ■ J~ ■■ ■ -T 4.00 • 46, _ • ` �^ram ■ � • � d jV �� • ~ i ■ / � ��-----�� TEA/�� ♦ • s � so- ■ 0.00 m o 0 0 o a 9 o ¢ .� o Town of Holly Springs 29 Wastewater Discharge Alternatives Evaluation & Expansion W15f20116:12:00AM HdlyspingsE Fire108_10_2011. a Figure 1-9 Effluent BOD & TSS trends 10.0 # Boos • TSS BA ® - ----•Poty.(BODS) '., ____• Poly. (TSSI 0 ooa - ♦ -I ------- a 6.0 E 0 c c -- 40 2.0 070 00 ODOM 0 0 0- 0 0 m oaDv m Gaup • gor ---� �- Im 0.0 O ry n � n Qi tj N C O 6 O Town of Holly Springs 30 Wastewater Discharge Alternatives Evaluation & Expansion B/1620118: 12:00 AM Holly Songs EAA FIne108_10_.2011.d= SECTION 2.0 - EVALUATION OF ALTERNATIVES 2.1 General Several Wastewater Management Options were evaluated in preparation of this EAA and the accompanying EA. These include No Action, Optimum Operation, Regional Solutions, UCWRF Discharge Relocation and Expansion. These alternatives were evaluated in the 2006 201/EA and WWRWRF FEIS. Feasible alternatives will be evaluated in the following sections. 2.1.1 Management Option A: "No Action" The "no action" alternative is not considered feasible because it would not meet immediate and projected needs for wastewater treatment capacity. The Town has invested nearly $29 million in the upgrade and expansion of its wastewater treatment facilities over the past 5 years to expand the treatment capacity to 6 mgd. With no further improvements, the usable capacity would be limited to the current NPDES discharge of 2.4 mgd, plus any reclaimed water usage. "No Action" would require future development to be served by private wastewater treatment facilities or septic tanks. Use of private wastewater treatment facilities is not considered acceptable because such facilities historically have resulted in poor quality effluent being discharged to receiving streams. Streams with sufficient assimilative capacity for new wastewater discharges are also unlikely to be available in the Town's service area. Septic tanks are also not acceptable on an extensive scale because many of the soils in Wake County have moderate to severe restrictions for septic tanks due to low soil permeability. In addition, projected development is expected to be at or near urban densities throughout the portion of the service area within the Town's growth areas and the adjoining county residential and commercial service areas. The lack of available wastewater capacity will also limit industrial development potential which in turn could have a negative economic impact on the Town's growth and development. Economic development has recently slowed, but is beginning to rebound. Competition for industry and the jobs industries provide is likely to be high as municipalities and the State of North Carolina try to recover from the current economic downturn. A lack of sufficient wastewater capacity could certainly result in lost economic development opportunities. Town of Holly Springs 31 Wastewater Discharge Alternatives Evaluation & Expansion 811=011 11:34:00 AM Molly Springs EAA Jinal 00 10 2011.docc This alternative will not be considered any further, as it does not meet the purpose and need of additional wastewater capacity for future growth, nor NCDWQ's desire to remove the discharge from the headwaters of Utley Creek. 2.1.2 Management Option B: Optimum Operation of Existing Facilities The existing UCWRF is currently permitted to discharge 2.4 mgd at the current location and was issued an ATC for 6.0 mgd. This facility is being operated to meet the current 2.4 mgd NPDES limits. The review of recent plant records (Section 1.7.4) indicates that the UCWRF is currently operating quite efficiently. DWQ has indicated it would not allow an expansion in the permitted capacity above 2.4 mgd at the current discharge location. While the existing facility could treat more wastewater and has received an ATC for 6 mgd, improvements are needed onsite to meet the speculative limits for nutrients provided by DWQ for 6 and 8 mgd. Optimal operation would not meet the growth needs of the town at the current discharge location since higher flow cannot be permitted there. Optimal operation would not meet the NPDES permit limits at an alternative discharge location. Thus, optimal operation does not meet the project purpose and need and is not considered further in this document. 2.1.3 Management Option C: Harnett County Regional Interconnection Under this Option, the Holly Springs would convey up to 8 mgd of wastewater to the North Harnett Regional WWTP at Lillington. Continuing to treat and discharge 2.4 mgd at the UCWRF and transferring 5.6 mgd to Harnett County was considered, however, this does not meet NCDWQ's desire to remove the discharge from the headwaters of Utley Creek. The WWRWRF FEIS and ROD evaluated this alternative for Holly Springs. The analysis completed for that document indicated that Harnett County would need to expand one of its treatment facilities to accommodate the flow from Holly Springs. In addition, this alternative would result in extensive impacts from a raw wastewater conveyance facility including stream crossing and wetland impacts and other risks from increased conveyance of raw wastewater. Based on the lack of capacity which does not meet the project purpose and need and the higher Town of Holly Springs 32 Wastewater Discharge Alternatives Evaluation & Expansion 8/18=11 11:34:00 AM Holly Springs EAA _Final 08 10 2011.docx environmental impacts associated with this alternative, it has been eliminated from further consideration. 2.1.4 Management Option D: Treatment at the Western Wake Regional WRF Under this Alternative, Holly Springs would construct a raw wastewater transmission system to convey 8 mgd to the WWRWRF site. The first phase of the WWRWRF has been designed and will begin construction in the Fall of 2011. This alternative was reviewed in the Western Wake FEIS as part of the various regional systems evaluated and was eliminated based on cost. To achieve the capacity needed, Holly Springs would have to purchase 8 MGD of capacity in the WWRWRF and a corresponding share in the WWRWRF effluent conveyance to the Cape Fear River. In 2006 the estimated capital cost of raw wastewater conveyance and treatment facilities for 3.6 mgd capacity exceeded $63m and the present worth exceeded $72m (all in 2006 dollars). The WWRWRF, which is about to go to construction, would likely need to be expanded or components redesigned to accommodate the additional flow from Holly Springs, resulting in additional expenses. The Western Wake Partners cannot delay their schedule due to interbasin transfer certificate requirements to return wastewater to the Cape Fear River and conveying raw wastewater to the proposed WWRWRF would not meet the purpose and need of that facility. The FEIS and ROD resulted in Holly Springs continuing to operate its own treatment facilities for flows of 6 and 8 mgd. Transferring raw wastewater would require the installation of major wastewater pumping station at Utley Creek, and a flow diversion system. The wastewater pump station and forcemain length and routing would be similar in scope to the Cape Fear River effluent conveyance alternatives (Alternative E-1), but would have the additional potential impacts of conveying raw wastewater rather than treated effluent. Continuing to treat and discharge 2.4 mgd at the UCWRF and transferring 5.6 mgd to the WWRWRF was considered, however, does not meet NCDWQ's desire to remove the discharge from the headwaters of Utley Creek. This option has higher impacts from conveying raw wastewater than treating at the current plant site, does not meet the WWRWRF purpose and need, and has a higher cost. Thus, it is eliminated from further detailed study. Town of Holly Springs 33 Wastewater Discharge Alternatives Evaluation & Expansion 8/18/2011 11:34:00 AEA Holly Springs EAA Jinal 08 10 2011.docx 2.1.6 Management Option E: UCWRF Expansion and Discharge Relocation The UCWRF has a current treatment capacity of 6.0 mgd and is permitted to discharge up to 2.4 mgd of wastewater into Utley Creek. In order to meet the projected wastewater flows of 8.0 mgd for the 2030 planning period, the Town would upgrade and expand the existing facility as needed to meet more stringent nutrient limits and relocate the discharge from the current location in the headwaters of Utley Creek. Potential alternatives for the discharge of the effluent from the UCWRF evaluated herein include: • Alternative E-1: Cape Fear River Discharge: This alternative assumes the effluent is conveyed to the WWRWRF and ultimately discharged into the Cape Fear River. This alternative was preferred in the 2006 201 Plan to comply with the NCDWQ desire to remove the discharge from Utley Creek. • Alternative E-2: Lower Utley Creek Discharge: This alternative assumes the effluent is conveyed downstream below Greentree Reservoir and is discharged into Utley Creek upstream of Harris Lake. • Alternative E-3: Land Application - This alternative assumes the effluent is land applied. • Alternative E-4: Wastewater Reuse - This alternative assumes the effluent is disposed of via combinations of landscape irrigation, industrial usage, and bulk reclaimed water. Details of each of the alternatives are discussed in more detail in the following sections, including a discussion of the UCWRF process improvements required to upgrade the facility to meet more stringent nutrient limit requirements now proposed for the Cape Fear River and the Lower Utley Creek alternatives. 2.2 Treatment Process Upgrades As previously noted, the UCWRF expansion was designed to meet NPDES effluent limits based on the Cape Fear River speculative limits, which were proposed at 2 mg/L TP and 6 mg/L TN. To achieve these goals the facility design included the following process components as described previously in Section 1.7: • A 5-stage biological nutrient removal (BNR) process Town of Holly Springs 34 Wastewater Discharge Alternatives Evaluation & Expansion 8/18/2011 11:3, 00 AM Holly Springs EAA Final 00_10 2011.docc e Secondary clarifiers with low surface loading rates e Cloth media tertiary filters (Kruger DiscFilters) e Supplemental coagulant chemical feed equipment The current 5-stage BNR process is capable of achieving effluent total nitrogen levels between 4.0 and 5.0 mg/L. The biological phosphorus uptake process is also generally able to achieve TP of 1.0 to 2.0 mg/L without any chemical precipitation. Generally accepted practice is to provide additional treatment processes when lower effluent levels are required by NPDES permit. During startup the UCWRF has been able to exceed these goals, however current hydraulic loading is only at 60% of the online units' rated capacity. This high level of performance is based upon the following operating criteria: e Suitable ratios of influent BOD5, COD, to nitrogen and phosphorus e Maintenance of proper levels of activated sludge (MLVSS) in the aeration basins e Proper management of biosolids wasting To ensure compliance with the potential effluent limits less than 2 mg/L TP and/or 6 mg/L TN, a variety of process upgrades could be incorporated into the existing wastewater treatment process, as discussed in this section. Identification of the needed upgrades will be addressed in the discussion of each individual discharge alternative (Sections 2.3 to 2.7) 2.2.1 Disc Filters Upgrade The existing cloth media disc filters are excellent for normal solids reduction, because they are relatively economical, have a compact foot print, and are easy to maintain. Disc filters also require a very small volume of backwash water compared to deep bed filters. Disadvantages with disc filters are the inability to operate in denitrification mode and a limited ability to chemically remove phosphorus. Consultations with the filter manufacturers have shown success in meeting a 0.5 mg/L TP limit with the current filter technology and the addition of a coagulant mixing system immediately upstream of the filter units. This would improve the efficiency of the chemical dosing system and the ability of the disc filters to remove effluent Town of Holly Springs 35 Wastewater Discharge Altematives Evaluation & Expansion 8/15/2011 8:12:00 AM Hoily Springs EAA _Final 08 10 2011.docx phosphorus. A fifth disc filter unit is also recommended to lower the solids loading rate and provide capacity for the 8 mgd flow with one unit out of service. 2.2.2 Deep Bed Denitrification Filters An alternative filter system utilizes deep bed filters for both normal solids reduction and denitrification of nitrates (NO3-N) to nitrogen gas, which is released to atmosphere. Denitrifying microorganisms attach to the filter media, which provides the support system for their growth. A carbon source such as methanol, acetic acid, molasses, etc. is added upstream of the packed - bed filter and a nitrified influent is filtered through the media. The deep bed filter system is well suited for denitrification because it provides the necessary hydraulic detention time for the biological reaction to take place. The filter media is composed of a coarse, hard, predominately siliceous material (sand). Configuration and operation is very similar to a conventional water plant filter system. The additional detention time and media also enhance chemical phosphorus removal, as compared to the existing disc filter, and some of the coagulant feed upgrades would not be necessary to meet the lower phosphorus limits. Preliminary sizing criteria for denitrification filters are based on a loading rate of 2 gpm/SF of filter area. A total filter area of approximately 2,780 square feet is needed to treat the 8 mgd design flow. Four filter cells, are recommended so that one cell can be backwashed without excessive loading on the remaining cells. Disadvantages to deep bed filters are higher capital cost, larger footprint, relatively high backwash rate of 6 gpm/SF, plus air scour, large capacity backwash pumps, backwash supply and waste storage, and filter scour blowers. An upgrade to denitrification filters will require the removal of the existing cloth media filters. 2.2.3 Supplemental Carbon Feed System As noted above, a supplemental carbon source is required for the denitrification filters to remove additional nitrogen. Supplemental carbon can also be feed into the second anoxic zone to enhance biological denitrification. Methanol is the most common carbon source used at Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly Springs EAA Jinal 08 10 2011.docx 36 wastewater facilities; however cost and availability of alternate source chemicals would be evaluated during design. Depending on the biological nitrogen performance and seasonal effluent limits, the amount of carbon added can be minimized to trim 1-2 mg/L of nitrates, or increased to remove up to 5 mg/L nitrates. A typical methanol feed system would include an 8,000 gallon storage tank, metering pumps, and ancillary equipment. An average feed rate would be a 100 gpd design capacity. The alternative carbon sources have varying chemical and physical properties, so it may become significantly more expensive to design storage and feed equipment to accommodate all possible compounds. 2.2.4 Coagulant Feed System UCWRF currently includes a coagulant feed system as a backup and enhancement for biological phosphorus removal. The current chemical feed system was designed as polishing step to remove about 1 mg/L TP to ensure compliance with the anticipated 2 mg/L effluent standard. It is common practice to provide chemical backup to BNR processes to assist during process upsets, seasonal changes, etc. Operating initially under the Town's current Utley Creek NPDES permit (2.4 mgd, equivalent 0.5 mg/L TP), the UCWRF has been able to successfully reduce TP to less than 0.20 mg/L with aid of chemical precipitation, albeit at high dosages and high chemical cost. The design was based on using ferric chloride as the coagulant because it is one of the more aggressive metal salt compounds, however the feed equipment can also be used with several aluminum compounds, and has initially been operated with sodium aluminate. As illustrated in Table 2-1 chemical usage could increase 3 to 7 fold to meet lower effluent phosphorus standards. As described in Disc Filter Upgrades, the filter supplier has recommended a new coagulant system to enhance effectiveness of the coagulant, additional of a polymer to enhance phosphorus removal. This would include a concrete mixing basin, vertical mixers; polymer feed system, additional bulk storage, and a new building to house the chemical feed equipment. Town of Holly Springs 37 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly springs EAA Final 08 10 2011.docx Table 2-1 Chemical Phosphorus Precipitation If denitrification filters are determined to be necessary for compliance with lower nitrogen levels, the disc filters would be removed. A separate coagulation mixing basin would not be needed but would be incorporated in the deep bed filter inlet channel. Additional coagulant bulk storage and a new building to house the chemical feed equipment would be needed. Common to either type of filter technology, compliance with lower phosphorus limits would require several associated improvements including additional chemical feed lines, an additional coagulant bulk storage tank and secondary containment structure, and metering pumps . 2.2.5 Biosolids Handling Upgrades The timely and efficient disposal of biosolids is critical to the overall operation of the treatment process, and especially so when achieving low nutrient levels. While nitrogen is ultimately converted to nitrogen gas, phosphorus is only removed from the waste treatment process via effluent, sludge wasting, or sludge screening/grit. The UCWRF Cannibal® Biosolids system includes a cyclone separator component to remove grit from the RAS and research has shown is effective in ultimate phosphorus removal. This grit stream can be disposed of in a municipal solid waste landfill. A second 0.95 MG Cannibal® Interchange Tank will need to be constructed. This component was not included in the initial construct because of conflicts with the current cascade aeration structure. The Interchange will be needed before the UCWRF reaches 3 mgd of waste flow, and lower nutrient limits justify its construction to provide operational flexibility. Town of Holly Springs 38 Wastewater Discharge Alternatives Evaluation & Expansion 811512011 8AIMAM Hdly SpMgs F _Fim108_10 2011 d. Research has also shown the Interchange Tank decant is high in phosphorus, and a Decant Clarifier can be added to maximize phosphorus removal. The sludge collected will be wasted directly to the aerobic digester. This component was initially included in the Upgrade and Expansion design, but construction was delayed to coincide with the second Interchange Tank. Finally, a Sludge Dewatering Facility is proposed to ensure biosolids can be wasted and disposed of without the seasonal and wet weather impediments associated with liquid land application. The Class B sludge cake can be stored onsite, then hauled away for agricultural land application, or converted into a Class A product by composting or drying. The proposed dewatering facility would likely include sludge pumps, polymer feed, a single belt filter press, and conveying system for truck loading. The entire system will be enclosed in a building to minimize odors and protect equipment. 2.2.6 Present Worth Cost Estimate A preliminary engineering level cost estimate shows the construction costs and contingencies for the improvements required for each effluent discharge alternative. The compound amount (F) in 2010 dollars was unchanged from recent (2008) cost estimates. Recent year construction costs are depressed, however, the conservative approach to account for variable construction market conditions is to neither inflate nor discount the previous cost estimate methodology. This also maintains consistency between the Town and Partners previous planning documents. A construction contingency of 10% and a professional services allowance of 15% has been used to calculate the total project costs. The Town's anticipated contribution to the Western Wake Partners is included, and is based on the Western Wake Partners' Engineering Report (Brown & Caldwell, June 2010) and subsequent data provided by the Town. The net present value cost estimate was calculated over a 20-year period using a discount rate of 4.875%. Town of Holly Springs 39 Wastewater Discharge Alternatives Evaluation & Expansion 811520118:12:00 AM holly Springs EAA _Final 08_10 2011.docx This Page Intentionally Blank Town of Holly Springs qp Wastewater Discharge Alternatives Evaluation & Expansion 8115=118:12:OOAM HdIy Spdngs EAA FiM108_102011.dM 2.3 Alternative 1: Cape Fear River Discharge 2.3.1 Background As previously discussed, the Holly Springs 201 Plan (2006) recommended an effluent conveyance system to the WWRWRF and a Cape Fear River discharge as the most viable alternative evaluated. The 201 Plan presented the infrastructure upgrades necessary to meet anticipated permit limits in the Cape Fear River at the current design capacity of 6.0 mgd and maximum month of 8.0 mgd. This document was referenced in the preparation of the Western Wake Partners' Environmental Impact Statement (FEIS) & Engineering Report (ER). The 201 Plan developed a routing for the Utley Creek Effluent forcemain to the Western Wake Partners proposed WWRWRF, located just north of Highway 1 and west of New Hill - Holleman Road. This location has been commonly identified as "Site 14" in the Western Wake Partners planning documents. During the Western Wake Partners EIS process, Site 14, along with several other possible sites, were evaluated for location of the Partners wastewater treatment facilities. Issuance of the USCAE ROD has confirmed the selection of Site 14 as the WWRWRF location. Figure 2-1 shows an overall layout of the proposed Holly Springs effluent conveyance system from UCWRF to the WWRWRF site. Effluents from the two WRF's would be combined and then conveyed and discharged into the Cape Fear River near Buckhorn Dam (Figure 2-2). The current UCWRF treatment process design was based upon the speculative limits issued by DWQ (December 2005). The final NPDES permit limits issued to the Western Wake Partners were more stringent than the speculative limits to reduce nutrient loading in the Cape Fear River, and this section's discussion is based on the final permit limits. Table 2-2 compares the 2004 Cape Fear speculative limits with the final Cape Fear River permit limits issued in January 2011. This alternative was included in the planning and design documents of the Western Wake Partners, including the FEIS and USACE ROD (July 2010). Holly Springs has completed preliminary design of the pipeline and pump station. The issuance of the USACE ROD satisfies the environmental review requirements for this alternative, and if implemented, USACE/DWQ 404/401 permit application can be submitted, along with an NPDES discharge permit application for the Cape Fear River. Town of Holly Springs 41 Wastewater Discharge Alternatives Evaluation & Expansion 8115/20118:12:00 AM Holly Springs EAA Jinal OS_10 2011.docx Table 2-2 Cape Fear River Discharge Limits Parameter Flow, mgd Cape Fear River rr• Spec Limits) Up to 8.0 Cape Fear River (Final 2011) Up to 8.0 BODS, mg/L' 5.0 (10.0) 5.0 (10.0) Total Suspended Solids, mg/L 30.0 30.0 Ammonia Nitrogen, mg/L 1.0 (2.0) 1.0 (2.0) Total Nitrogen, Ibs/day 4002 Mass basedon 3.5 mg/L Total Nitrogen, mg/L ---- 5.0 Total Phosphorus, lb/day 133 3 Mass basedon 0.5 mg/L Total Phosphorus, mg/L ---- 0.75 Fecal Coliform, #1100 mL 200 200 Dissolved Oxygen, mg/L 6.0 6.0 pH, units 6-9 6-9 'Season limits, summer April -October (winter November -March) 2 Mass limits based on 6 mg/L TN and the permitted flow 3 Mass limits based on 2 mg/L TP and the permitted flow ° Monthly maximum concentrations (April to October) 5 Mass based TN and TP limits (April to October) 2.3.2 New Infrastructure Currently, the plant discharges treated effluent from the UV disinfection process through a gravity ouffall and cascade aerator into Utley Creek. To convey flow to the WWRWRF, an effluent pump station and forcemain are required. The new effluent pumping structure will be constructed west of the UV facilities. The effluent structure will include four vertical turbine pumps for effluent transfer and three vertical turbine reclaimed water supply pumps. The wetwell will be divided to allow the reclaimed water to be shut down during periods of non-compliance with reclaimed standards. The reclaimed water Town of Holly Springs 42 Wastewater Discharge Alternatives Evaluation & Expansion 8/152011 8:1200 AM Holly Springs EAA ffinal 08_10 2011.d= chlorination facilities will also be relocated to the effluent pump station area, and chlorine contact time will be provided to comply with reclaimed water standards. All pumps will be provided with variable frequency drives to match flow rates and minimize electrical operating costs. To meet reliability standards, a new standby diesel generator is proposed for the effluent pumping system. A new building will be provided adjacent to the new pump station to house chemical feed equipment, controls, and electrical switchgear. The effluent forcemain will be a 36" diameter pipeline, with an overall length of 35,400 LF. As shown in Figure 2-1, the majority of the forcemain route parallels existing public roads; however temporary and permanent easements will be required in several locations due to stream crossings, utility conflicts and topographic features. Compliance with the more stringent phosphorus limits (0.5 to 0.75 mg/L TP) could be achieved by chemical precipitation; however the lower summer nitrogen limits (less than 3.5 mg/L TN) will require more extensive process modifications. To ensure compliance with the more restrictive nutrient limits the following process modifications are recommended, as shown on Figure 2-3 and described in more detail in Section 2.2: • Replacement of existing Disc Filters with deep bed Denitrification Filters • Supplemental Carbon Feed System • Upgraded Coagulant Feed System • Biosolids Handling Upgrades including the Decant Clarifier, additional Interchange Tank, and Sludge Dewatering Facilities The Western Wake Partners construction contracts would include the forcemain piping on Site 14 (north of Highway 1) and structures to receive the Holly Springs effluent. An effluent pump station will be constructed by the Western Wake Partners to convey the combined effluents to the Cape Fear River via about 11.75 miles of 60" diameter forcemain. Town of Holly Springs 43 Wastewater Discharge Alternatives Evaluation & Expansion 8115=118:12:00 AM Holly Springs FAA _FIrral 08 10 2011.docr Table 2-3 Alternative E-1: Cape Fear Discharge Present Worth Cost Estimate Estimated Costs Pipe Material $4,263,695 Valve Costs $113,400 Air Release Valves $72,000 Fitting Cost $135,200 Equipment/Labor Cost $1,188,000 Erosion Control $177,000 Seed/Restoration $122,000 Rock Excavation $1,770,000 Trenchless Cost $625,000 Denitrification Filter Upgrades $4,900,000 Supplemental Carbon & Coagulant Systems $425,000 Biosolids Facility Upgrades $2,339,000 Effluent Pump Station $2,250,000 Subtotal $189380,300 Contractor OH&P, Bonds, Insurance $3,037,200 16.5% Total Construction Estimate $219417,500 Professional Services $3,212,600 16.0% Contingencies $2,141,800 10.0% Western Wake Expenses $12,967,400 Total Capital Cost $399739,300 Present Worth Pipeline O&M $675,600 Present Worth Effluent Pumping O&M $2,069,300 Present Worth Advanced Treatment O&M $4.602,700 Total Present Worth $47,086,900 Town of Holly Springs 44 Wastewater Discharge Altematives Evaluation & Expansion $115MOI1 s:l2:oowu nary Springs emu► Fnal0810 2011.doc)c The proposed work on the existing UCWRF site has no wetlands or stream impacts, however construction of the effluent forcemain has associated impacts, as summarized in Table 2-4. Table 2-4 Potential Environmental Impacts Pipeline Construction to WWRWRF Site Temporary Permanent Perennial Stream Crossings 3 each None Intermittent Stream Crossings 3 each None Wetland Impacts, acres 0.13 0.03 Town of Holly Springs 45 Wastewater Discharge Alternatives Evaluation & Expansion 8/1520118:12:00 AM Holly SpMgs EAA _Flml 08_10_2011.Oou This Page Intentionally Blank Town of Holly Springs 46 Wastewater Discharge Alternatives Evaluation & Expansion 811U2011 8:12:00 AM Holly Springs EAA _Final 08 10 2011.doac r 5y �� ®" 5� Legend do pggg cU� � �� I N < O W— Elfluenl Forcemain V� x U51 ono _ + � `� •$ � � ¢ a a .Q I I uueysre H(&Y SPRINGS —Fa _ sae 1aa _aere WWRWRF y Wake_MafolRoatle_2010_ A�n 03 FRI Nl.up �' FFE� l Wake_S4eeb_2010_03 S7eams E RIF�- y i.7N SHIh FRI N�SFIIa � `➢P � � 9 � Wake_Juriad1ction_2009_11 / 9N a w � $$ x f OL YSPRING5 NE HILL "Am%0 Up0 E 330" EFFLUENT o ¢ RCE NY�4IN 9� _ TH MILt r, yAnelySl ����.", ✓ m HOLLY SPRINGS rc C a -- THOMAS MILL 8 ' GREENTREE ' POND •., ARRIS LAKE RESERVOIR � QP o � w -- F: f rEHT }ER ---T N 1 inch = 2,500 feet Town of Holly Springs Figure 2-1 w E Engineering Alternatives Analysis Cape Fear Discharge Alternative E-1 dmp Discharge Alternatives Evaluation Proposed Forcemain Route S � This Page Intentionally Blank Town of Holly Springs 48 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly Springs EAA_Final 08 10 2011.docx iat W-�A' Poplar uckhorn,e RWRF Site r� 55 UC RF ife e DI �-- Legend 49UtleySite 55 1 WWRWRF Site Effluent Forcemain WWRWRF Effluent Ha nett � _ _ _ Cnty Bnds (detailed, named) N 1 inch = 7,500 feet Town of Holly Springs Figure 2-2 w E Engineering Alternatives Analysis Alternative E-1 : Cape Fear Discharge S �P Discharge Alternatives Evaluation Overall Layout of Effluent System This Page Intentionally Blank Town of Holly Springs 50 Wastewater Discharge Alternatives Evaluation & Expansion 8115120118:12:00 AM Holly Springs FAA _Fina108 10 2011.docx RECLAIMED PUMP STA z CLARIFIER 1 CLARIFIER #2 JLATION FILTERS f UV FILTERS DECANT CLARIFIER AB 3 ANOXIC/ REAIR l_ AD 2 ADMIN. IrARIFIER BLDG. #3 AB 1 SLUDGE PS I P S SLUDGE I DEWATERING L"`-- PROPERTY LINE IT BLOWERS_�T_ - - - -SLUDGE& RECLAIMED TRUCK LOADING TOWN OF HOLLY SPRINGS ENGINEERING ALTERNATIVES ANALYSIS DISCHARGE ALTERNATIVES EVALUATION GRAPHIC SCALE 80 40 0 80 FIGURE 2-3 UTLEY CREEK WRF UPGRADED SITE - ALTERNATIVE E-I This Page Intentionally Blank Town of Holly Springs 52 Wastewater Discharge Alternatives Evaluation & Expansion 811520118:1200 AM Holly Spdngs EAA _Final 0810 2011.docc 2.4 Alternative E-2: Harris Lake Watershed Discharge 2.4.1 Background When Holly Springs received their 2.4 mgd discharge permit to discharge in the headwaters of Utley Creek, DWQ indicated that they would not permit any additional flow at this location and advised the Town to explore other options. Holly Springs commissioned Tetra Tech to conduct an analysis of Utley Creek in 2004 as part of the planning for the UCWRF Expansion. The most significant, potential water quality impairment was identified at that time in Thomas Mill Pond where chlorophyll -a levels have exceeded the 40 ug1L water quality standard and algal blooms have been observed. Significant effects in the vicinity of the Greentree Reservoir were not observed because this impoundment is quite small and several of the flashboards had been removed. Tetra Tech's report concluded that in general Utley Creek's water quality could improve with improved level of treatment and increasing flow from the UCWRF but exceedance of the chlorophyll -a standard might continue in Thomas Mill Pond. While these findings were positive, the Town did not pursue this option at the time because of DWQ's position on moving the discharge. Also, at that time, the Town could not afford lengthy delays in the UCWRF expansion project because of the urgent need for additional capacity in the rapidly developing service area. The option of a discharge into Harris Lake was first evaluated in 2008 by the Western Wake Partners. Preliminary modeling conducted by the Western Wake Partners indicated this was a viable option, albeit with much lower effluent phosphorus limits than the 2005 Cape Fear River speculative limits. The scenarios evaluated included both a combined and separated WWRWRF and UCWRF outfalls into Harris Lake, various effluent flows, and elevated Harris Lake levels. All indicated that the level of chlorophyll -a in Harris Lake could be maintained within current water quality standards. The modeling also showed minimal differences in chlorophyll -a between the combined and separate WWRWRF and UCWRF outfall scenarios. A Final Technical Memorandum prepared by CH2M Hill (February 2010) summarizes the modeling process. The Western Wake Partners were forced to abandon the Harris Lake discharge due to requirements in Cary and Apex's interbasin transfer (IBT) certificate. Modifications to an IBT are a lengthy process, which would have created excessive delays in the Partners project. Town of Holly Springs 53 Wastewater Discharge Alternatives Evaluation & Expansion 8/18/2011 8:12:00 AM holly Springs EAA _Final 08 10 2011.doac 2.4.2 Holly Springs Speculative Limits When the Western Wake Partners elected not to pursue this option, the Town of Holly Springs retained CH2M Hill to continue the monitoring modeling process to further evaluate the UCWRF discharge into Harris Lake. This analysis was continued through 2009 and summarized in a Speculative Limits Request and Technical Memorandum (CH2M Hill, December 2009) which is provided in Appendix B. The point of analysis used is representative of a discharge directly to the White Oak Creek arm of the lake near New Hill -Holleman Road Bridge. Progress Energy also indicated support of the UCWRF discharge remaining within the Harris Lake watershed. After meeting with the DWQ NPDES Unit, this modeling and analysis led to the issuance of the speculative limits for Harris Lake shown in Table 2-5. The speculative limits granted by DWQ are more stringent than the original Cape Fear and comparable to the final Cape Fear discharge limits included in the Final NPDES Permit for Western Wake WRF issued on January 7, 2011. The limits for total nitrogen (TN) and total phosphorus (TP) are attainable using advanced treatment technologies. After receiving speculative limits for Harris Lake, the Town reopened investigations into a continued discharge into Utley Creek due to the significant cost and potential wetland impacts associated with a pipeline to the lake. A review of DWQ planning documents indicated that Utley Creek is not listed as an impaired water body. During 2010 and 2011 the Town, its consultants, and DWQ's Planning and Permitting Staff revisited the possibility of continuing to discharge effluent into Utley Creek. The Town initiated a monitoring program in 2009 to determine the current conditions in Utley Creek and the two smaller impoundments. The monitoring results showed water quality improvements since 2004, however there were still elevated chlorophyll -a levels detected in Thomas Mill Pond. Continued discharge to the headwaters of Utley Creek upstream of Thomas Mill Pond was eventually ruled out based on the potential for algal blooms and water quality issues in Thomas Mill Pond. Two additional discharge locations, Location "A", just below Thomas Mill Pond, and Location "B", just below Greentree Reservoir, were subsequently evaluated. Results of this effort are documented in Evaluation of Proposed Utley Creek Discharge which is included as Appendix D. Town of Holly Springs 54 Wastewater Discharge Alternatives Evaluation & Expansion 8H5/20118:12:OO AM Holly Springs EAA _Final 08_10 2011.docx This memorandum includes a description of the QUAL2E water quality model of Utley Creek from Thomas Mill Pond to Harris Lake, results of the monitoring program, and the potential changes in water quality from 6mgd and 8mgd discharges at Location "A" or location "B". Greentree Reservoir is not presently impounded, as all flashboards have been removed from the dam. However, Progress Energy has proposed a pilot wetlands project at Greentree to simulate the Harris Lake expansion to 240' MSL, which would reinstall some of the flashboards. The QUAL2E model simulated the Greentree Reservoir being operated in a partially submerged state as planned by Progress Energy. This evaluation confirmed that up to an 8 mgd discharge at either location would not adversely impact water quality and may improve water quality in the lower sections of Utley Creek. A discharge at Location A, above Greentree Reservoir was eliminated based on uncertainty about Progress Energy's plans to operate Greentree Reservoir, and concerns about water quality in Greentree Reservoir when impounded. A speculative limits request was made for Location B, in the lower reach of Utley Creek, approximately 0.7 miles above Harris Lake. Location B is preferred over discharge directly into Harris Lake for the following reasons: • An outfall into the lake body would require an additional 5,500 LF of effluent pipeline, with increased capital cost. • The majority of the pipeline below Greentree Reservoir would be submerged by the proposed Harris Lake expansion. This is due to the relatively level topography along Utley Creek approaching the White Oak arm of the lake. • Additional stream and wetland impacts associated with the lake discharge. DWQ issued speculative limits for Lower Utley Creek at Location "B" in June 2011 (Appendix B). The numerical limits were the same as those previously issued for Harris Lake and are summarized in Table 2-5. Town of Holly Springs 55 Wastewater Discharge Alternatives Evaluation & Expansion 811 SI2011 8:12:00 AM hilly springs EAA Final 05102011.doc x Table 2-5 Harris Lake Watershed Discharge Limits Flow, mgd 2.4 6.0 & 8 BOD5, mg/L' 5.0 / 10.0 5.0 Total Suspended Solids, mg/L 30.0 30.0 Ammonia Nitrogen, mg/L' 1.012.0 1.0 Total Nitrogen, Ibs/day 2 120 ----- Total Nitrogen, mg/L ---- 5.0 Total Phosphorus, lb/day 3 10.0 ----- Total Phosphorus, mg/L 0.5 0.50 Orthophosphate, mg/L ---- 0.27 Fecal Coliform, #/100 mL 200 200 Dissolved Oxygen, mg/L 6.0 7.0 PH, units 6-9 6-9 ' Dual limits are summer / winter season 2 Current permit limits are expressed in lb/year and based on 6 mg/L TN Current permit limits are expressed in lb/year and based on 0.5 mg/L TP 2.4.3 New Infrastructure This alternative assumes that the effluent from the UCWRF will be conveyed by gravity along Utley Creek to a point below Greentree Reservoir. A layout of this alternative is presented in Figure 2-4. The proposed discharge location (referred to as Location "B") is just below Greentree Reservoir and approximately 0.7 miles upstream of the current 220' MSL lake level. A discharge structure could be constructed on the stream bank without extensive impacts within the Utley Creek or the lake bed. Final design of the outfall pipeline will include several drop manholes to provide re - aeration and a cascade structure will be designed near the discharge point to aerate the effluent to meet the 7.0 mg/L DO requirement. The stream elevation at this point is approximately 234' Town of Holly Springs 56 Wastewater Discharge Alternatives Evaluation & Expansion 8115W 18:12'.00 AM Holly Spnngs EAA Jimal 08_10_201 lo. MSL, so if Harris Lake is expanded to the proposed 240' MSL a minimal amount of piping would be submerged and no additional structures required. Available GIS data was used to route the pipeline and supplemented with field reviews to minimize the potential environmental impacts of this alternative. The pipeline has been routed along existing cleared corridors to the extent possible in an effort to minimize potential wetland, stream, and other impacts to the environment as well as impacts to individual property owners. The anticipated nitrogen limits can be achieved with the current 5-stage BNR process, however additional of supplemental carbon into the 2nd Anoxic stage is desirable to ensure complete denitrification occurs in the process. Denitrification filters typically would not be needed to meet a 5 mg/L effluent TN. Upgrades to optimize phosphorus removal are needed, especially with the low 0.25 mg/L orthophosphate limit, and an additional disc filter has been recommended. The following UCWRF treatment process upgrades are recommended, as described in more detail in Section 2.2: • Supplemental Carbon Feed System into Second Anoxic Zone • Coagulation Basin, upgraded Coagulant Feed System, additional disc filter • Biosolids Handling Upgrades including the Decant Clarifier for phosphorus wasting, additional Interchange Tanks, and Sludge Dewatering Facilities Ancillary improvements at the UCWRF will be required since an effluent pump station will not be constructed. These include an effluent flow metering structure and reclaimed water pumping station to be constructed to the west of the current UV disinfection facility. Demolition of the existing structures are necessary to allow room for the new decant clarifier and interchange tank. These UCWRF improvements are shown on Figure 2-5. The proposed work on the existing UCWRF site has no wetlands or stream impacts; however construction of the effluent ouffall has associated impacts, as summarized in Table 2-6. The estimated costs of this alternative are summarized in Table 2-7, as well as the net present worth of this alternative. The Town's share of the Western Wake Partners expenses has been reduced by eliminating participation in effluent conveyance construction. Town of Holly Springs 57 Wastewater Discharge Alternatives Evaluation & Expansion W15R0118:12:00 AM Hdly Spdrgs EAA _FmI08_10_2011AM Table 2-6 Potential Environmental Impacts Outfall Pipeline Construction Temporary Permanent Pipeline Length, feet 11,700 11,700 Perennial Stream Crossings 4 each None Intermittent Stream crossings 3 each None Wetland Impacts 0.10 0.06 Table 2-7 Alternative E-2: Lower Utley Creek Discharge Present Worth Cost Estimate Estimated Costs Pipe Material $2,255,715 Manhole Materials $276,000 Equipment/Labor Cost $480,000 Erosion Control $140,400 Seed/Restoration $60,000 Rock Excavation $1,170,000 Trenchless Cost $375,000 Phosphorus Removal Upgrades $409,000 Supplemental Carbon & Coagulant Systems $425,000 DiscFilter Upgrades $693,000 Cascade Aerator $343,000 Relocated Reclaimed Water Pump Station $468,000 Biosolids Facility Upgrades $2,339,000 Subtotal $9,434,000 Contractor OH&P, Bonds, Insurance $1,558,000 16.5% Total Construction Estimate $10,992,000 Professional Services $1,648.800 15.0% Contingencies $1,099,200 10.0% Western Wake Expenses $837,000 Total Capital Cost $14,677,000 Present Worth Pipeline O&M $223,300 Present Worth Effluent Pumping O&M WA Present Worth Advanced Treatment O&M $5,001,100 Total Present Worth $19,801,400 Western Wake Expenses, estimate from Town of Holly Springs. Town of Holly Springs 58 Wastewater Discharge Alternatives Evaluation & Expansion 8115=118:1200 AM Hdly Spdrge EAA _nre108_10_2011AM 11 s., 6 HARRIS LAKE I PROPOSED 48" "OUTFALL\ r r f{l 7GRIEENTRE;ESERVOIR PROP' DISCHARGE LOCATION 1 l i MILL w K O -Y OILY SPRINGS NEW HIL Legend Lower Utley Creek Outfall Harris Lake (Future 240') w WRF-structures o x S MILL UCWRF Site O 0 WWFWRF Site w ; Wake_MajorRoads_2010_03 g TRAD ON aWake_ Streets_2010_03 HILL JLakes, Ponds RIDGE Streams Incorporated Areas EXISTING UCWRF \ PE_HAR_Wetlands g Ji. Fff a 14U 0 N 1inch =1,500feet Town of Holly Springs Figure 2-4 W E �;: Engineering Alternatives Analysis Alternative E-2: Lower Utley Creek Discharge Discharge Alternatives Evaluation Proposed Outfall Route S = This Page Intentionally Blank Town of Holly Springs 60 Wastewater Discharge Alternatives Evaluation & Expansion 8115=11 8:12:00 AM Molly Springs EAA Final 08 10 2011.docx 0 N N CLARIFIER 1 ANOXIC/REAIR JIL� b- I _ ADMIN. CLARIFIE CLARIFIER BLDG. #2 #3 EFFLUENT & I NEW _ _ RECLAIMED I DENITE PUMP STA I FILTER SH 1 BLIP S. UV FILTERS' DECANT CLARIFIER IPS SLUDGE DEWATERIN� .ice s I PROPERTY f LINE UTLEY CREEK - J IT BLOWERS -- _SLUDGE& RECLAIMED TRUCK LOADING ' TOWN OF HOLLY SPRINGS ENGINEERING ALTERNATIVES ANALYSIS DISCHARGE ALTERNATIVES EVALUATION GRAPHIC SCALE 80 40 0 80 FIGURE 2-5 UTLEY CREEK WRF UPGRADED SITE - ALTERNATIVE E-2 This Page Intentionally Blank Town of Holly Springs 62 Wastewater Discharge Alternatives Evaluation & Expansion 811620118:12:00 AM Holly Springs EAA _Final 08 1 U 2011.docx 2.5 Alternative E-3: Land Application The use of spray irrigation as an alternative to surface water discharge was analyzed as part of the Town's long-range study in 1996 and the 201 Plan (2006). The quantity of well -drained soils in the Holly Springs area is highly limited. Areas with Appling, Cecil, and Norfolk soils are most desirable, but they are primarily found in areas of Town and the ETJ that are already developed, or are now being developed. Mayoden and Pinkston soils are fairly desirable for irrigation, and are present just west of Holly Springs, on Progress Energy's "Harris Gamelands" property. The Harris Gamelands site has approximately 350 acres of suitable soil conditions. At conservative loading rates of 0.5 inches per week, this site could only support about 0.69 mgd of wastewater. Other large tracts of land that could be irrigated have poor drainage qualities and are too steep for land irrigation systems. See Figure 2-6. The land application alternative involves the construction of treated effluent storage and land application (irrigation) facilities. These facilities would be located at a dedicated land application site. The land application site would require a cover crop to take up the moisture and nutrients from the wastewater effluent. The land area required for land application of a wastewater volume equal to the 8.0 mgd capacity is estimated at approximately 3,100 acres. This is based on a conservative land application rate of 0.67 inches per week through a spray irrigation system. The spray fields would be cultivated with suitable annual crops, timber, etc. Additional land would be required for buffers from property lines, residences, water, and drainage features as well as for 30 day effluent storage (240 million gallons) lagoons. The additional land area required for ancillary facilities and buffers is estimated to be 500 acres (15%), for a total area of approximately 3,600 acres. Table 2-8 presents a cost summary of the land application alternative. Since no specific sites have been identified, the costs of pumping and transmission infrastructure required to convey the flow from the UCRWF to the land application site cannot be defined. The preliminary cost estimates include an effluent pumping station similar to Alternative E-1, but does not include a force main cost. For this same reason environmental impacts were not estimated. Town of Holly Springs 63 Wastewater Discharge Alternatives Evaluation 8 Expansion 811520118:12:00 AM Holly Soling EAA Fiwl 08_10_2011.dou Purchasing the necessary land may also prove problematic as the potential areas are in Wake County and NC GS 153A-15 would prohibit the Town from purchasing the land without the consent of the Wake County Commissioners. The high cost of the land required, plus the additional facilities for treatment and effluent transportation make this alternative more costly than any other alternatives. The conclusions of previous studies are still valid. The high cost of land, limited suitability of area soils, and cost of treatment and application facilities make this option non -cost efficient. For these reasons, land application is not considered a feasible alternative. Town of Holly Springs 64 Wastewater Discharge Alternatives Evaluation & Expansion 8/15/2011 8:12:00 AM Holly Springs EAA Jinal 08 10 2011.doac Table 2-8 Alternative E-3: Land Application Present Worth Cost Estimate Estimated Costs 30 day Holding Tanks/Lagoons $7,345,000 Effluent Pump Station $2,250,000 Electrical Work $200,000 Spray Irrigation Piping $16,938,347 Fence $903,000 Access Roads $350,000 Erosion Control and Seeding $4,705,096 Spray Field Maintenance & Operations Equipment $85,000 Nutrient Removal Upgrades $0 Cascade Aerator $0 Biosolids Facility Upgrades $2,339,000 Subtotal $359115,000 Contractor OH&P, Bonds, Insurance $5,801,000 Total Construction Estimate $40,916,000 Professional Services $6,137,400 Contingencies $4,091,600 Land Acquisition $36,100,000 Western Wake Expenses $837,000 Total Capital Cost $88,082,000 Present Worth Pipeline O&M NIA Present Worth Effluent Pumping O&M $2,069,300 Present Worth Advanced Treatment O&M NIA Present Worth Land Application O&M $3,148,800 Total Present Worth $93,300,100 16.5% 1 15.0% 10.0% Does not include force mains to convey effluent from the UCWRF to unknown land application sites. Western Wake Expenses, estimate from Town of Holly Springs. Town of Holly Springs 65 Wastewater Discharge Alternatives Evaluation & Expansion 811 W011 8:12:00 AM Holly springs EAA Jinal 08 10 2011.Cocx This Page Intentionally Blank Town of Holly Springs 66 Wastewater Discharge Alternatives Evaluation & Expansion 811 srz011 8:12:00 AM Holly springs EAA _Final 08_10 2011.doc x OL SPRINaS�NI 1 N'4y LLY SPRINGS g �' Legend WRF- IWdures THOMAS MILL i� HarrlsG-1.,.ds y`� ----- UCWRFS1W ' / 0 WWFWRF SR. W Streams / K T�D/%/Oj� lakes, POMs i a Harris lake (Future Wake Streets 2010 03 Wake_MejorF2oads_2010_03 NTINE I—rp,-tedA.- HOLLYSPRI S UCWR� —1 de THOMAS MILL POND (7 U ,v GREEN TREE i RESERVOIR �= p M6A00W J�0 dFR� Oi2E. ID � L. AVE T DOWS SYCAM �� C RACAN Qkr CO FALL c F H 1 inch = 1,000 feet Town of Holly Springs Figure 2-6 WE dm Engineering Alternatives Analaysis Alternative E-3: Land Application S EP Discharge Alternatives Evaluation Potential Sites This Page Intentionally Blank Town of Holly Springs 68 Wastewater Discharge Alternatives Evaluation & Expansion 8115/20118:12!00 AM Holly Springs EAA Jinal 08 10 2011.docx 2.6 Alternative E-4: Wastewater Reuse The Town of Holly Springs has implemented a new Reclaimed Water System, which was just placed into service in the summer 2010. Reuse of treated effluent is an option that could relieve the quantity of wastewater discharged into the waters of the states via NPDES discharge. An overview of the current service area is shown in Figure 2-7. Water reuse systems in the central region of North Carolina are predominately landscape irrigation -based systems that experience high demands during the hot, dry summer season, and little to no demands during the cool, wet winter season. To effectively reduce the volume of NPDES discharge capacity on a year-round basis, commercial and industrial users are a necessity. The Town of Holly Springs Reclaimed Water System has been planned as a component of larger planning initiatives of the Town, including the Comprehensive Land Use Plan and the Secondary & Cumulative Impacts Master Mitigation Plan (SCIMMP). Both of these documents comprise a comprehensive planning program aimed at allowing the Town to develop in a manner that minimizes adverse environmental impacts and preserves the valuable environmental resources in the Holly Springs area. Wastewater reuse is only one part of the overall program, which also encompasses transportation planning, erosion and sediment control, storm water management, potable water and wastewater planning, and open space and recreation planning. A Wastewater Reuse Master Plan was developed in 2000 to guide the Town in the phased construction of its reuse system. The specific objectives of the Master Plan are to support the overall objectives of the SCIMMP by minimizing actual wastewater discharges, conserving potable water supplies, and protecting potable water quality. Holly Springs' approach to wastewater reuse is a part of a broadly focused, balanced planning process intended to conserve high quality water supply sources as well as to minimize the volume of wastewater discharged. Holly Springs, while predominately residential, is building an industrial and commercial customer base, and actively promotes reclaimed water for process and cooling needs as much as practical. Industrial and cooling water users are less subject to seasonal peaks than irrigation, and therefore allow for consistent year-round utilization of reclaimed water. These type users will Town of Holly Springs 69 Wastewater Discharge Alternatives Evaluation & Expansion W1520118:1200 AM Hdlyspiings EAA _Ri 08_10_201tE Y accomplish two goals, the minimization of wastewater discharges and conservation of potable water supply. The initial Holly Springs Reclaimed Water System was constructed from 2006-2010. This initial phase, including supply pumps, chlorination, distribution piping and an elevated tank, provides reclaimed water to a service area north of the UCWRF which includes the Holly Springs Business Park, Twelve Oaks golf course, and Twelve Oaks residential development. Bulk Water will also be available at the UCWRF site for contractors, landscapers, and other approved users. Initial estimates for reclaimed water use have ranged from 90,000 gpd during winter months to 750,000 gpd on peak summer time days. The Town plans to implement additional phases of Reclaimed Water distribution as economic and customer demands allow. All of the newer and proposed subdivisions within the Reclaimed Water Service Area are planned to include "purple pipe" distribution systems for future use. Holly Springs is committed to maximizing the reclaimed water usage to the extent possible. Since the Holly Springs' primary reclaimed water customer base at this time consists of residential seasonal users and irrigation systems, implementation of the Reclaimed Water System will not significantly reduce the NPDES discharge volume. Discharge of the full treated volume may be required during winter months; however, with the seasonal demand peaking in summer, the effluent loading on the receiving waters will be significantly reduced during the more sensitive warm weather months. Still, as a full alternative, wastewater reuse is not considered a viable alternative at this time and no cost estimate can be provided. Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 811520118:12:00 AM Holly Springs EAA Final 08102011.docx 70 44 0 l'I IE TOWN OF Holly Springs NORTH C,AROLINA Reclaimed Water Map Base Man Data ujJ a T—Nea •a¢ao�Mee wr., 1[I nem ReuseP mO S,a'wn • ReW mN Tam ------ 6n Reuse Wa�e�rc ��� 1)n Reuu WAeRro ]M R¢uu Water ne •••........ Unknown $¢¢Reuse Figure 2-7 Reclaimed Water System This Page Intentionally Blank Town of Holly Springs 72 Wastewater Discharge Alternatives Evaluation & Expansion 8115n011 8:12:00 AM Holly Springs EAA ffinal 08 10 2011.d= 2.7 Alternatives Evaluation & Summary Potential wastewater management alternatives were developed and evaluated in the preceding pages. After initial review, Alternative E-4: Wastewater Reuse, and Alternative E-5: "No Action", were determined not feasible as they are not capable of meeting the project purpose and need. The present worth costs for the alternatives are summarized in Table 2-9 below. A review of the present worth costs shows Alternative E-2: Lower Utley Creek Discharge, to be the most economically and environmentally attractive and feasible alternative. . Table 2-9 Present Worth Cost Summary Notes: 1) Present worth analysis based on 20 year planning period with a discount rate of 4.875% 2) NTF -Not Technically Feasible for this Project 3) Western Wake Expenses are based upon Partners Cost Estimates provided by the Town, and are included in the Capital Cost shown 4) Land costs for Alternative E-3 are assumed to be 50% salvage value The preferred Alternative for the Town's wastewater discharge is Alternative E-2: Lower Utley Creek Discharge. Table 2-10 summarizes the project elements and impacts of the feasible alternatives evaluated in this report and the accompanying Environmental Assessment. Town of Holly Springs 73 Wastewater Discharge Alternatives Evaluation & Expansion 8n5Q011 e:12.00 AM Hay springs EAA_Final 08_70 2011.d= Table 2-12 Alternatives Summary Preferred Alternative Alt. E-1 Alt. E-3 Alt. E-2 Lower Utley Cape Fear River Discharge Land Application Creek Discharge Net Present $19.8 M $ 47.1 M $93.3 M Worth Phosphorus 0.50 TP 0.75 winter N/A Limits, mg/L 0.27 OrthoP 0.50 summer Nitrogen 5.0 5.0 winter N/A Limits, mg/L 3.5 summer Denitrification No Yes No Filters Phosphorus Removal Yes No No Upgrade supplemental Coagulation & Yes Yes Yes Carbon Feed Biosolids Yes Yes Yes Upgrades Effluent Pump Station No Yes Yes Effluent Line 11,700 35,400 TBD (LF) Gravity Forcemain Wetland 0.10 temp 0.13 temp TBD Impacts (ac) 0.06 perm 0.03 perm Stream Impacts 3 intermittent 3 intermittent TBD 4 perennial 3 perennial Town of Holly Springs 74 Wastewater Discharge Alternatives Evaluation & Expansion &1WO118:12:00AM Holly Springs E Final OB_102011.d= SECTION 3.0 - REFERENCES 1. Town of Holly Springs, Utley Creek Wastewater Treatment Plant. 201 Facilities Plan Amendment. Davis -Martin -Powell & Associates & Green Engineering . August 2006. 2. Town of Holly Springs, Reclaimed Water System. Engineering Report. Davis -Martin -Powell & Associates. April 2007. Final Environmental Impact Statement for the Western Wake Regional Wastewater Management Facilities. CDM and CH2M HILL. 2010. http://www.saw.usace.army.mil/Wetlands/Proiects/WW- WTP/index.html 3. Record of Decision, Western Wake Regional Wastewater Management Facilities. U.S. Army Corps of Engineers. July 2010. http://www.saw.usace.army.miUWetiands/Proiects/WW- WTP/index.html 4. Town of Holly Springs, Secondary & Cumulative Impact Master Mitigation Plant. CH2M HILL. Updated bi-annually by TOHS. http://www.hollvspdnosnc.us/dept/engineering/scimp/index.htm 5. Modeling Analysis of the Holly Springs WWTP Nutrient and BOD Discharge Impact on the Utley Creek Watershed. Tetra Tech, Inc., July 2004. 6. Technical Memorandum, Evaluation of Potential Holly Springs Discharge Scenarios. CH2M HILL. December 2009. 7. Harris Lake Discharge Evaluation Technical Memorandums (Final Compilation). CH2M HILL. February 2010. 6. Western Wake Partners, Western Wake Regional Wastewater Management Facilities. Engineering Report. Brown & Caldwell. June 2010. http://www.westernwakepartners.com/documents.htmi 9. Technical Memorandum, Evaluation of Proposed Utley Creek Discharge. CH2M HILL. June 2011. Town of Holly Springs 75 Wastewater Discharge Alternatives Evaluation & Expansion 8/1520118:12:00 AM Holly Springs EAA_Fi,M108_10_2011.d= This Page Intentionally Blank Town of Holly Springs Wastewater Discharge Alternatives Evaluation & Expansion 8115/20118:12:00 AM Holly Springs EAA _Final 08 10 2011.docx 76