2015 HDR, Inc., all rights reserved.

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1 2015 HDR, Inc., all rights reserved.

2 Hastings Utilities Water Pollution Control Facility Improvements Brian Bakke, HDR ASCE Environmental Conference 4/6/2017

3 Review Existing Facilities Need for the Project Study Phase Design Phase Construction Phase Start-Up and Operation

4 01 Review Existing Facilities

5 Existing Facility Site Plan

6 Existing Facility Rotating Biological Contactors (not in operation) Trickling Filter provides bulk of treatment

7 02 Need for the project Permit Limits

8 Permit Limits - Ammonia Existing permit (effective July 1, 2008) includes transition to final lower ammonia limits Condition Permit Compliance Dates January 31, 2012 Submit Design for Upgrades June 30, 2012 Initiate Construction April 2014 Be in Compliance 2003 Permit 2008 Permit Interim 2008 Permit Final Fall and Winter Ave. 8.1 mg/l 8.7 mg/l 2.48 mg/l Spring and Summer Ave. 8.5 mg/l 8.1 mg/l 1.88 mg/l

9 Study: Future Flows and Loadings Residential growth projected at 0.5% per year. Same as Water Master Plan Year Population , , , , ,872

10 Industrial Contributions Prior to June 2009 Influent to PCF % industrial wastewater Since July 2009 two major industries have not been in operation. New tenants plan on resuming operation in the near future. Discussions with each industry helped establish projected flows and loads when they resume operation. (60% of previous contributions) Industrial reserve of built into planning numbers to account for potential future industries.

11 Projected Flows

12 Projected CBOD Loadings

13 Existing Facility: Trickling Filter Biochemical Oxygen Demand (BOD) removed before ammonia is removed. High BOD load does not leave enough room for ammonia removal zone. Inflow Outflow BOD Removal Zone Ammonia Removal Zone

14 Existing Treatment Facility Existing plant has capacity to meet interim permit with trickling filter through 2015 with some reserve for industry Existing plant does not have capacity to meet final permit limits, even at current loadings. Additional facilities are needed to achieve the new limits. What should be built and how much?? What other regulatory drivers should be considered??

15 Future Permit Limits Future Permit Scenarios Considered: 10 mg/l TN and 1.0 mg/l TP (7-12 years) 5 mg/l TN and 0.5 mg/l TP (15-20 years) 3 mg/l TN and 0.3 mg/l TP (>20 years)

16 Recommended Improvements: Evaluation Methodology Long Term Improvements Short Term Current Limits Lower Ammonia Limits 10 mg/l TN 1 mg/l TP 5 mg/l TN 0.5 mg/l TP 3 mg/l TN 0.3 mg/l TP Regulatory Timeline

17 Improvements to Meet Existing Ammonia Limits Three options evaluated for existing final ammonia permit limits Activated sludge lowest cost option All options utilized the existing Trickling filter in a parallel mode operation Cost Component Alternative 1 Activated Sludge Alternative 2 - IFAS Alternative 3 - MBBR Estimated Capital Costs $8,680,000 $8,050,000 $10,250,000 Estimated Present Worth O&M Costs Total Present Worth Life Cycle Costs $1,880,000 $2,890,000 $3,930,000 $10,560,000 $10,940,000 $14,180,000

18 Proposed Site Plan for Recommended Improvements

19 03 Study Phase

20 Study Methodology Long Term Improvements Short Term Current Limits Lower Ammonia Limits 10 mg/l TN 1 mg/l TP 5 mg/l TN 0.5 mg/l TP 3 mg/l TN 0.3 mg/l TP Regulatory Timeline

21 Evaluation of Future Limits (10 mg/l N and 1 mg/l P) Cost Component Number of Trickling Filters in Service Alternative 1 Trickling Filters with Activated Sludge Alternative 2 BNR Activated Sludge Alternative 3 Hybrid Process Two Zero One Estimated Capital Costs $16,430,000 $12,300,000 $10,420,000 Estimated Present Worth O&M Costs Total Present Worth Life Cycle Costs $5,341,000 $2,827,000 $2,678,000 $21,771,000 $15,127,000 $13,098,000

22 Implementation Plan Plan developed for future more restrictive permits Chosen Path Forward by the City Permit Limit Existing Final Ammonia 10 mg/l Nitrogen 1 mg/l Phosphorous 5 mg/l Nitrogen 0.5 mg/l Phosphorous 3 mg/l Nitrogen 0.3 mg/l Phosphorous Estimated Timing Now 7-12 years years >20 years Estimated Capital Cost $8,680,000 $1,740,000 $2,500,000 Increase in Operational Cost $10,420,000

23 04 Design Phase

24 Design Criteria 2030 Avg Annual Max Month Peak Day Flow MGD CBOD lbs/day 10,300 17,800 29,600 mg/l TSS lbs/day 8,600 14,600 26,300 mg/l NH3 lbs/day 930 1,370 4,470 mg/l Peak WW flow 15 MGD

25 Design Site Layout

26 Enhanced Nitrification BNR Activated Sludge - ENBNRAS Influent Screen Grit Removal Primary Clarifiers Anaerobic Anoxic Aerobic Secondary Clarifiers (14-FT SWD) Final Effluent A B MLR A RAS B WAS B Primary Digestion Secondary Digestion Lagoon Storage Land Application

27 Nitrification Only

28 Nitrogen Removal

29 Full BNR Mode

30 Aeration Basin Effluent Design BNR Basin Aerobic Anoxic Anaerobic Aerobic Anoxic CS No. 8 PE Splitter Anoxic Anoxic Anaerobic `

31 Design BNR Basin Aerobic MLR Anoxic MLR Anaerobic Aerobic MLR Anoxic CS No. 8 PE Splitter Anoxic Anoxic MLR Anaerobic ` Aeration Basin Effluent To Inter. Clar.

32 Design BNR Basin Aerobic MLR Anoxic MLR Anaerobic Anoxic CS No. 8 PE Splitter Aerobic MLR Anoxic Anoxic MLR Anaerobic ` CS No. 10 Trickling Filter Effluent Splitter Aeration Basin Effluent To Inter. Clar. CS No. 9 RAS Splitter

33 Design BNR Basin Anaerobic, Anoxic and Aerobic zones 194 length x 46 width x 22 tall concrete tank Fine Bubble Diffusers 9 Membrane Discs Submersible Mixers (3 per train) 10 HP Mixed Liquor Recycle Pumps (2 per train) Anoxic to Anaerobic 2,000 GPM, 10 HP Aerobic to Anoxic 4,900 GPM, 40 HP

34 Design BNR basin

35 Design Pump/Blower Building 4 RAS pumps VTSH type 2,500 GPM, 40 HP 2 WAS Pumps Self Priming 250 GPM, 7.5 HP 2 ILS Pumps VTSH Type 5,600 GPM, 40 HP 4 High Speed Turbo Blowers 2,500 SCFM, 150 HP VFD Stand by Generator Electrical and Control Room

36 Design Pump/Blower Building

37 Design Final Clarifier Final Clarifier 80 Diameter Stainless Steel Mechanism

38 Design Site Layout Aeration Basin Lift Station Final Clarifier

39 Design Bid Results Bid in April 2012 Four Bids Eriksen Construction John T Jones Construction PKG Contracting BRB Contractors $10,431,000 $10,970,000 $11,096,000 $11,782,000 Project awarded to Eriksen Construction, Blair, NE Engineers Estimate - $11.5 million

40 05 Construction Phase

41 Construction Timeline Contract Price: June 2012 Eriksen issued Notice to Proceed January 15, 2014 Substantial Completion March 15, 2014 Final Completion Contractual Dates 85-90% Complete Mid-Late November Startup activities begin Bid: $10,413,000 Final: $10,487,000 Change Orders: 0.7%

42 Aeration Basin

43 Electrical Room MCC

44 Pump Room

45 Pipe Gallery Dry well area

46 West Exterior View

47 Final Clarifier

48 06 Start-Up and Operation

49 Parallel Flow Process Will be used at startup Allows staff to become familiar with AS Operational cost savings

50 Influent Loadings

51 Effluent Quality

52 Effluent Quality

53 Nitrogen Removal Performance

54 Effluent Phosphorus

55 Questions