Pierre Comprehensive Water Study

Transcription

1 Pierre Comprehensive Water Study Pierre City Commission February 27, 2018 Presented by: Advanced Engineering and Environmental Services, Inc. (AE2S)

2 The Team Pierre Dane Brewer John Childs Kristi Honeywell Kyle Kurth Derek Myhre Brad Palmer Gidget Palmer Lynn Patton AE2S Brian Bergantine Trevor Datwyler Delvin DeBoer Greg Hanson Miranda Kleven Kevin Smith Richard Wagner Brian Weiss

3 Objectives Plan for the future water supply needs of Pierre Identify sources Evaluate water treatment options Evaluate distribution system

4 Approach Project future water needs Evaluate Existing System Review water supply sources Review regulatory requirements of sources/treatment options Evaluate treatment plant site alternatives Review treatment alternatives Assess pros/cons of alternatives Prepare preliminary cost estimates Recommend alternative

5 Future Water Needs Design Year = 2045 Estimated population x per person water use = average day demand Average day demand x peaking factor = max day demand Design flow rate = max day demand

6 Population 19,000 18,000 17,000 16,000 15,000 14,000 13,000 12,000 11,000 10,000 9,000 8,000 7,000 Pierre Population Trends and Projected Growth 6, Year 16,100 Pierre Census Pierre Census Estimate Hughes Census Hughes Census Estimate 2008 Water Study Population Projection Linear (Pierre Census)

7 Estimated Water Production = 2045 Design population = 16,100 Average Day Production = 2.72 MGD Max Day Production = 8.8 MGD Factors affecting peak day = population growth, lawn watering Conservation measures can reduce future peak day, perhaps in the range of 0.5 MGD WTP production capacity 8.8 MGD

8 Existing System 12 Wells 3 Pressure Zones 3 Pump Stations 4 Reservoir Locations Generally in good condition Well pump/motors serviced routinely Older reservoirs at Euclid and Harrison showing structural age Electrical modifications recommended at several well locations

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10 Average Well Flow Rates (gpm) Total Average Well Production (gpm) July 2017 Average Well Production vs Number of Pumps Operating 8.4 MGD 6,000 5, , , Additional wells are needed to meet the design flow of 8.8 MGD Number of Pumps Operating 2,000 1,000 0 Well 1 Well 2 Well 3 Well 5 Well 6 Well 7 Well 8 Well 9 Well 10 Well 11 Well 12 Well 13 Total Production

11 Existing Water Quality Water Quality Characteristics Manganese (2.4 mg/l) Hardness (345 mg/l) Sulfate (360 mg/l) Dissolved Solids (850 mg/l) General trend to higher TDS Wells 6, 7 and 11 have trended to highest concentrations Remaining wells are trending upward, but not as severely Sulfate is increasing Hardness is increasing Distributed water meets requirements of the Safe Drinking Water Act

12 Water Treatment Provided at each well Fluoride (some wells) Sequestering chemical (inhibit Fe/Mn precipitation) Chlorine combines with ammonia to form chloramine for disinfection

13 Distribution System Evaluation Updated previous hydraulic model infrastructure Calibrated the updated model Used the model to evaluate Hydraulic requirements for water treatment plant sites Water storage hydraulics and water age Pipe requirements for new areas Available fire flow Sizes of replacement pipes

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15 Source Alternatives Missouri Aquifer expand existing well field Missouri River new intake Nearby Regional Water Systems Mid Dakota Rural Water Oglala Sioux Rural Water Supply Systems

16 Water Sources (Quality) Missouri Aquifer (wells) Manganese (2.4 mg/l) Hardness (345 mg/l) Sulfate (360 mg/l) Dissolved Solids (850 mg/l) Missouri River Manganese (0.03 mg/l) Hardness ( mg/l) Sulfate ( mg/l) Dissolved Solids ( mg/l) Significant upward trend in TDS Long Term Consistency

17 River System Treated Water Comparison TDS Sulfate Hardness Alkalinity System mg/l mg/l mg/l as CaCO3 Softening Systems Mobridge Chamberlain Clarification Systems WEB Mid Dakota Oacoma Aurora Brule Pierre (2013)

18 SDWA Regulatory Requirements Primary Drinking Water Standard Requirements Revised Total Coliform Rule D/DBP Rule Lead/Copper Rule Radionuclides Arsenic SOCs / VOCs UCMR Manganese Secondary Drinking Water Standards (recommended) Parameter Standard Pierre River Manganese, mg/l Sulfate, mg/l TDS, mg/l

19 Surface Water Treatment Regulations DBP Rule Remove natural organic matter Surface Water Treatment Rules Remove Turbidity Additional disinfection requirements for specific organisms

20 Treated Water Objectives Comply with Safe Drinking Water Act primary drinking water standards Eliminate staining (remove manganese/iron) Minimize taste/odor If possible, match quality of treated river water

21 Well Source - Manganese (and Iron) removal Oxidation/ Detention Settling Filtration Disinfection Removes colored water issue High TDS, sulfate and hardness in the treated water Quality is inferior to surface water Existing well infrastructure is used replace wells 6, 7, 11 and add wells to meet 8.8 MGD Raw water pipeline, water treatment plant, treated water pipeline

22 Oxidized and Precipitated Manganese

23 Wells - Manganese (Iron) Removal with RO Oxidation/ Detention Settling Filtration Disinfection Reverse Osmosis Removes colored water issue Use RO to adjust TDS, sulfate and hardness to desired levels Quality is equivalent to or better than surface water RO concentrate discharge to River (no lime softening sludge) Existing well infrastructure is used replace wells 6, 7, and 11 and add wells to meet 8.8 MGD Raw water pipeline, water treatment plant, treated water pipeline

24 Surface Water Treatment Pretreatment Membrane Filtration Disinfection Removes colored water issue Meet Surface Water Treatment Rule requirements (turbidity and organism removal) Matches adjacent surface water system treated water quality Requires development of surface water intake Raw water pipeline, water treatment plant, treated water pipeline

25 WTP Alternative Sites

26 Site 3 - Ramkota West of Ramkota Between railroad and Highway bridges Site 4 Steamboat Park South of highway bridge West of Dakota Ave. Both sites can be served by wells and surface water intake

27 Surface Water Site 4

28 Well Water Fe/Mn/RO Site 4

29 Alternative Evaluation 6 Alternatives 3 Treatment alternatives at each of two sites Non-Economic Evaluation (relative ranking of alternative against decision criteria) Economic Evaluation (capital costs, O&M costs, life-cycle costs) Combined score

30 Alternatives Alternative Source Site Treatment 1 Wells 3 - Ramkota Mn/Fe Removal 2 Wells 3 - Ramkota Mn/Fe Removal/RO 3 River Intake 3 - Ramkota Ultrafiltration 4 Wells 4 - Steamboat Mn/Fe Removal 5 Wells 4 - Steamboat Mn/Fe Removal/RO 6 River Intake 4 - Steamboat Ultrafiltration

31 Non-Economic Evaluation Alternative must meet Safe Drinking Water Act Requirements Alternative capacity must be at least 8.8 MGD Alternative must be capable of eliminating discoloration treated water manganese less than 0.05 mg/l

32 Ranking Criteria Category Stakeholder Impacts Treatment Operations System Operations Implementation Objective City of Pierre Impacts Customer Impacts Construction Impacts Public Safety Process Stability/Reliability Maintenance Chemical Use Residuals Management Staffing Requirements Integration of Existing Facilities Supply Reliability Treatment Redundancy Accommodating Additional Contaminants Water Source Acquisition CIP Impacts Long-Term System Flexibility and Security

33 Non-Economic Performance Score Alternative KT Scoring Total 7,706 8,214 9,843 8,392 8,900 10,718 KT Performance Score

34 Life Cycle Costs Present value of capital costs and operation and maintenance (O&M) costs Alternative Present Value $/Gallon MGD Ramkota Site - GW, Fe/Mn Removal $31,925,500 $ MGD Ramkota Site - GW, Fe/Mn Removal, with RO $44,161,500 $ MGD Ramkota Site - SW, UF $36,996,500 $ MGD Steamboat Site - GW, Fe/Mn Removal $31,540,100 $ MGD Steamboat Site - GW, Fe/Mn Removal, with RO $43,760,200 $ MGD Steamboat - SW, UF $37,421,800 $4.25

35 Composite Ranking of Alternatives Alternative KT Scoring Total 7,706 8,214 9,843 8,392 8,900 10,718 KT Performance Score Present Value Cost $31,925,500 $44,161,500 $36,996,500 $31,540,100 $43,760,200 $37,421,800 Cost Performance Score Composite Score

36 Recommended Alternative Surface Water Source Steamboat Park Site 8.8 MGD Ultrafiltration Water Treatment Plant Benefits Eliminate discoloration Softer Water (approximately 30% less salt usage) Reduce dissolved solids discharge to the river by approximately 2,000,000 lb/yr Better tasting water Good site access

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39 Water Bill Impact Random Customer Sample Customer Johnson Barringer Harding Huizenga Mehlhaff Childs Hight Average Current 2018 Rates $71.95 $53.40 $26.90 $56.05 $58.70 $64.00 $32.20 $51.89 Estimated New Rate $ $86.23 $42.63 $90.59 $94.95 $ $51.35 $83.74 Average Treated Water Additional Cost/month $44.80 $32.83 $15.73 $34.54 $36.25 $39.67 $19.15 $31.85

40 Monthly Water Bill Analysis Random Customer Sample Month Monthly Ave. Use, ccf Cost Using 2018 Rates Estimated Treated Water Rate Average Treated Water Additional Cost Jan 7 $29.55 $46.99 $17.44 Feb 6 $26.90 $42.63 $15.73 Mar 5 $24.25 $38.27 $14.02 Apr 4 $21.60 $33.91 $12.31 May 10 $37.50 $60.07 $22.57 Jun 20 $64.00 $ $39.67 Jul 31 $93.15 $ $58.48 Aug 34 $ $ $63.61 Sep 30 $90.50 $ $56.77 Oct 20 $64.00 $ $39.67 Nov 12 $42.80 $68.79 $25.99 Dec 6 $26.90 $42.63 $15.73 Average 15.4 $51.85 $83.69 $31.83

41 Impact on Water Rates For residential customer using approximately 8 ccf per month (average about 6,000 gallons per month), water bill increases by approximately 60 cents per day Random user analysis water bill increase by approximately $1 per day.

42 Mitchell, SD (2017) Watertown, SD (2017) Pierre, SD (2018) Sioux Falls, SD (2017) Aberdeen, SD (2017) Spearfish, SD (2017) Vermillion, SD (2017) Huron, SD* (2017) Brandon, SD (2017) Sturgis, SD (2017) Ft Pierre, SD (2017) Brookings, SD (2017) Madison, SD (2018) Harrisburg, SD* (2017) Pierre, SD (New WTP ) Yankton, SD (2018) Mid-Dakota, SD (2018) 2017/2018 WATER CHARGES South Dakota Systems $27.86 $30.94 $32.25 $32.29 $32.60 $32.95 $33.05 $33.92 $34.85 $35.98 $37.00 $37.60 Water Fixed Charge Water Volume Charge Based on 6,000 Gallons (8.02 CCF) $44.42 $46.20 $51.44 $55.04 $69.00 $0.00 $10.00 $20.00 $30.00 $40.00 $50.00 $60.00 $70.00 Typical Monthly Residential Water Bill ($)

43 QUESTIONS? Pierre City Commission February 27, 2018