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RESOURCE MANAGEMENT ISSUESIN REGIONAL WASTEWATER PLANNING

Ken Halll and Kip Duchon2

AUTHORS: lp.E., Water Resources Engineer; and 2p.E., Senior Environmental Engineer, CH2M HILL, 115 Perimeter Center Place,N.E., Suite 700, Atlanta, Georgia 30346-1278.REFERENCE: Proceedings o f the 1993 Georgia Water Resources Conference, held April 20 and 21, 1993, at The University of Georgia,Kathryn J. Hatcher, Editor, of Natural Resources, The University of Georgia, Athens, Georgia.

Abstract. This presentation describes a regionalwastewater planning effort involving four counties, threeregional planning agencies, and a study area about 510square miles in size. The study focused on consensus de-velopment, coordinationof short- and long-term solutions,and equitable sharing of financial and administrativeburdens.BACKGROUND

The 510-square-mile study area (Figure 1) lies in theEtowah River basin and includes the tributary area ofPumpkinvine Creek. Pumpkinvine Creek originates inPaulding County and flows into Bartow County prior tojoining the Etowah River.Historically, wastewater planning in the study area hasnot been coordinated on a re,gional basis. Most of thepopulation is served by on-site"septage systems; however,some small treatment facilities serve limited service areas.In 1990 the four counties (Bartow, Cherokee, Cobb, andPaulding) each petitioned the Georgia EnvironmentalProtection Division (EPD) of the Department of NaturalResources for additional wastewater discharge capacity inanticipation of projected growth. EPD recognized theneed for a coordinated approach to wastewater manage-ment in the basin and responded with a request for acoordinated plan.To address the common resource management issues,the counties developed a Technical Advisory Committee(TAC) composed of the leaders of each county'swastewater utility. The TAC was charged with developinga coordinated wastewater plan for a short-term (year 2011)and a long-term (year 2050) horizon. CH2M HILL andWelker & Associates were retained to facilitate the plan-ning effort and provide technical support in the planningprocess.

METHODOLOGYThe methodology of the study followed five basic steps:1) Review existing systems,2) Project flows and loads,

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3) Develop alternatives,4) Evaluate alternatives, and5) Develop consensus.Each step was accomplished through one or more tasksand workshops.Review Existing Systems. The review of existing

systems provided the study with a snapshot of existingconditions in the basin and allowed identification ofstrategic facilities which would ultimately be incorporatedin the long-range plan.

Table 1. 2011 Wastewater Flow Projections PumkinvineCreek/Etowah River Wastewater Managment Plan

LOTUS 123 - 201lR.WKI ..... Updatod: 10115192ALLWAYS - 2 OI IR .ALl . K . Hal II CH2M HIWATL ATL33483.A 1.04I s - - . - Ana ;;:: 'JIo:::- . . . -...... S-WFlaw

(-ad)IC;;OI Z.I J,UII ; t . IN Co2 \,2 1.716 1.340 0.12Co3 29.5 44.l14 98 43,391 4.19Co4 11.2 17.656 99 .17.479 1.93COS 15.1 22.263 99 22.040 2.37CobbSu--.ry 59.7 89.114 97 16.445 UICII Ill.1 J4.'):l1I :: oN./J4 12 6.1 6.661 6.06101 3 12.9 17.015 so 1,$43 0.7701 4 5.9 10,731 10 1.5" 0.7701 5 36.3 41.939 so 24,4-,0 2.2001 6 37.2 25.097 so 12.S4t 1.1301 7 5 U61 61 5.471 0".49a.t 5.6 5.190 is 3,239 0.29


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Figure 1. Study Area

Figure 2. Study Subbasins and Subareas

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Project Flows and Loads. Flow and load projectionswere developed from corresponding population tions. The study area was divided into 39 distinctsubbasins representing relatively homogeneous land use,topography, and geography (Figure 2). Area planningagencies provided the basic population information fromwhich 1991 populations were estimated, and the year 2011population estimates were projected for each subbasin.Population estimates for the year 2050 projections werebased on estimates of ultimate development densities (Le.,High, Medium, Low, Managed Low, Exurban) in eachbasin (Duchon et aI., 1991). The percentage of thepopulation that was sewered was estimated for eachsubbasin for 1991, 2011, and 2050.The correspondingflows were computed ona pe r capita basis, which varied' according to developmentdensity to account for employment (Tables 1 and 2). The

per capita flows also included an infiltration/inflowcomponent (EPA, 1991). Loads were then estimated usingrepresentative wastewater concentrations from metroAtlanta utilities.

Develop Alternatives. Alternatives were developed byfirst outlining the feasible options for serving each of 16subareas (created by grouping similar subbasins). Fivebasic options were considered for each subarea.1) Interceptor sewers and a publicly owned treatmentfacility discharging to surface waters.2) Interceptor sewers and a publicly owned treatmentfacility using land application of effluent for disposal.3) Interceptor sewers to transport wastewater to anothersubarea.4) Force mains and pump stations pumping effluent toanother subarea.5) No interceptors or publicly owned treatment facilities;all wastewater handled using on-site septage systems orsmall private land application systems.Alternatives were composed of a combination of theseoptions for each subarea, each with its own centralstrategy. Examples of strategies include maximizing theuse of land application, maximizing lake discharge, anddeveloping a regional plant. Five detailed alternativeswere developed for the year 2011 conditions. Seven alter-natives were developed, evolving from the initial five, forthe year 2050 conditions. Figure 3 is a schematic of Alter-native 1 for the year 2011.

Evaluate Alternatives. The evaluation of alternativesinvolved developing and weighting evaluation criteria,scoring alternatives, and computing numerical compositescores weighted by criterion. The evaluation criteria, andthe corresponding weights assigned by the T AC, are shownbelow: PoliticallPublic Acceptance 1.00 Environmental Effects 0.59

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Cost 0.40 Operational Reliability 0.15A weight of 1.00 represents the most importantcriterion in the T AC's estimation. The weights weredetermined by allowing each member of the TAC to judgethe importance of each criterion to the successful comple-tion of the project on an absolute scale of 1 to 10 (1representing the most important). The median value wasdetermined for each criterion, and the lowest median wasassigned a weight of 1.00. The remaining weights arelinear transitions of the medians.After discussing the issues related to each alternative,the TAC independently scored (on a scale of 1 to 10) eachalternative relative to each criter ion except Cost. Costscores were assigned based on the relative present worthcosts, including annual costs and salvage value, of eachalternative.The composite score of each alternative was computedusing the weights for each criterion. Thus an alternativescoring poorly on the PoliticallPublic Acceptance criterionwas penalized more in the scoring than an alternativescoring poorly on Operational Reliability.

Develop Consensus. The TAC met in a workshop todiscuss the results and develop a consensus on a recom-mended wastewater management alternative for the studyarea. The results of the numerical evaluation indicatedthat a decentralized treatment facility configuration wasmore favorable for the year 2011 conditions than one ortwo large regional facilities.Alternative 1 received the best overall score in thenumerical evaluation; based on the evaluation results andthe TAC's collective judgment , it was identified as the pre-ferred alternative. In addition, the selection of Alternative1 allows the option of implementing any of several favor-able year 2050 alternatives. These include two alternativesevolving directly from Alternative 1, and another alter-native characterized by decentralized facilities andpumping of effluent to a discharge point on the EtowahRiver downstream of Lake Allatoona.

CONCLUSIONSProviding appropriate information to the TAC for theselection process, and periodically discussing the issues

critical to each county in the workshops, helped develop aconsensus on the recommended alternative. Considera-tion of short-term alternatives that were compatible withlong-term solutions increased the efficiency and flexibilityof the recommended alternative. In addition, the costs ofthe plan were equitably distributed between the countiesbecause of the project's long-term perspective.The final recommendations included a list of actionitems and an implementation schedule for each county.


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Also identified were environmental issues to be addressedin implementing the recommended alternative.

ACKNOWLEDGMENTSThe authors gratefully acknowledge the cooperation

and support of the members of the TAC (Gene Camp,Harrison Collett, Dan Guill, and Tim Cole) and theBartow County Water Department, the Cherokee CountyWater and Sewerage Authority, the Cobb County WaterSystem, and the Paulding County Water System.

LITERATURE CITEDDuchon, Kip; William Zieburtz; and Gary Cornell.Utilization of Land Use Coefficients to Forecast UtilitySystem Demand. Proceedings of he 1991 Georgia Water

Resources Conference. University of Georgia.EP A Handbook of Sewer System Infrastructure Analysisand Rehabilitation, EPA/625/6-91/030, October 1991.

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