Hoodland Treatment Facility

Transcription

1 WBG PDX WBG PDX Hoodland Treatment Facility Investigating Indirect Discharge Options Along the Sandy River October 24, /24/2012 1

2 Agenda Background Initial Screening Evaluation of Short Listed Alternatives Conceptual Design Initial Predesign Efforts

3 Clackamas County Service District No. 1 Hoodland Service area: Hoodland, Welches and the Wemme Recreational Corridor Population served: 4,000 Start up: 1982 Design capacity: 0.9 million gallons per day Average yearly flow: million gallons per day Major Processes: Rotating biological contactor, secondary treatment, aerobic biosolids digestion, chlorine disinfection

4 January 2011 Flood Damaged Outfall in the Sandy River

5 Project Drivers & Goals Clackamas County Service District No. 1 desire for more resilient infrastructure Compatible with County s disaster preparedness and sustainability efforts

6 Hoodland Design Flows Parameter Flow, mgd Average Design Flow 0.9 Peak Flow 2.25

7 Hoodland STP Historical Effluent Flow

8 Hoodland STP Effluent Flow Frequency Distribution

9 Team and Stakeholders Randy Rosane WES Project Manager Jim Fisher WES Soils Program Supervisor Amy Kyle Public Information Specialist Mike Kuenzi WES Director Many other WES employees Numerous local area community groups and local residents/landowners Greg Geist and Bill Mason DEQ CH2M HILL consulting team

10 Project Goal Study Phase Determine a feasible discharge alternative that is not adversely impacted when Sandy River floods

11 Initial Alternatives Base Case. Sandy River diffuser replacement Indirect discharge at Timberline Rim Indirect discharge at Emigrant Trail Lane area Golf course and forest lands irrigation Irrigation/indirect discharge at Wildwood Recreation Area

12 Next steps XXX

13 Evaluation Criteria EVALUATION CATEGORY Water quality permitting CRITERIA NPDES/WPCF Permit Environmental permitting Financial Costs Additional Considerations Environmental Permits O&M Complexity Lifecycle Capital Cost Land Acquisition or Control Reliability of Approach Public Acceptance Potential Benefits from wetland banking or ecological credit River Water Quality Improvement Sustainability Implementation/Schedule Phasing/Expandability

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15 Order of Magnitude Cost Assessment Alternative Relative Project Cost Factor A Replace existing outfall 1 B - Indirect discharge at Timberline Rim C Indirect discharge at Emigrant Trail Lane 3 to to 3 D Irrigation with storage 11 to 20 E Irrigation & indirect discharge at Wildwood 12 to 22

16 Conclusion of Preliminary Screening Conduct Additional Evaluation of Indirect Discharge Alternatives Alternative Conclusion A Replace existing outfall B - Indirect discharge at Timberline Rim C Indirect discharge at Emigrant Trail Lane D Irrigation with storage E Irrigation & indirect discharge at Wildwood Continue to Consider as Base Case Evaluate Further Evaluate Further Not Consider Further Not Consider Further

17 Initial Public outreach Gauge community CPO/Community groups Sandy River Basin Watershed Council

18 Disposal of Municipal Wastewater Treatment Plant Effluent by Indirect Discharge to Surface Water via Groundwater or Hyporheic Water Internal Management Directive (IMD) September 2007 DEQ 10/24/

19 Potential Indirect Discharge Concept A

20 Potential Indirect Discharge Concept B for Emigrant Trail Lane area

21 Oregon DEQ s IMD for Indirect Discharge General Definition Municipal wastewater discharged to an indirectly to surface water via groundwater Establishes boundaries of a waste management area (WMA) in which treated effluent mixes with groundwater Concentrations of wastewater constituents in groundwater and hyporheic water within the waste management boundary may exceed background groundwater quality and still satisfy the requirements of OAR ;

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23 Oregon DEQ IMD requirements As required by the Groundwater Quality Protection rules in OAR , groundwater outside the waste management area will not be adversely affected Unlikely to create long term contamination WMA following termination of the discharge A local government or special district owns or otherwise controls the property containing the waste management area Virtually impossible that water supply wells do not exist and cannot be placed within the waste management area

24 Eventually Water Environment Services would need to show this no likely adverse groundwater quality impact could occur outside the waste management area boundaries. Control of WMA property Water supply wells do not exist and cannot be placed within WMA WMA limited in extent based on either a conservative design or on sufficient site-specific hydrogeologic data.

25 DEQ Indirect Discharge IMD: so addressed as follows WMA part of treatment system; may exceed groundwater quality in WMA (similar to in-stream mixing zones) Possibly avoid groundwater compliance points (and subsequent concentration limits or variances) Still comply with surface water quality or TMDL requirements that apply Possible groundwater monitoring to confirm design assumptions (i.e., detection monitoring points) or to ensure compliance with surface water quality permit conditions.

26 This Predesign Effort Can Be Costly

27 Preliminary Evaluation of Indirect Discharge Alternatives Utilize Existing Information Assess drinking water wells Begin to assess hydraulic conductivity Develop preliminary sizing and costs

28 Review of Oregon Department of Water Resources Well Logs

29 Investigation of Water Districts

30 Timberline Rim ponds Not many private drinking water wells; County owned Great potential for water quality benefits Pipeline: ~2.5 miles

31 Emigrant Trail Lane area Not many drinking water wells; County owned Favorable geomorphology Pipeline: ~0.6 to 1mile

32 Updated Preliminary Project Cost Estimates for Indirect Discharge Options Alternative Timberline Rim Emigrant Trail Project Cost Estimate $ 8 million $ 4 million

33 Conclusion of Alternatives Evaluation Proceed with Conceptual Design of Emigrant Trail Alternative Field work to begin to understand groundwater flow direction Assess design and permitting needs

34 Emigrant Trail Site Investigations Dig test pits at Emigrant Trail Lane area: Observe soils Install groundwater monitoring equipment

35 Emigrant Trail Test Pits

36 Test Pit Installation

37 Feet Below Ground Surface Groundwater Depth at Emigrant Trail Lane TP1 TP2 TP

38 Conclusion of Preliminary Design Effort Proceed with Predesign Emigrant Trail Lane site preferred Timberline Rim site as backup Continue community engagement

39 Conclusion of Preliminary Design Effort (cont.)

40 Predesign Initial Field Work Predesign Effort Well Installation Water quality monitoring Pump Test Determination of Ordinary High Water Elevation Objective Obtain groundwater levels and enable pump test Establish baseline Refine hydraulic conductivity Better define environmental permitting Wetlands Delineation Understand groundwater/river Surveying relationship

41 River Changes Dramatically and Quickly Mid September 2012 Early October 2012

42 Proposed Monitoring Wells

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45 Well Drilling Soil Characterization No glacial till encountered 0 to 15 ft: silt and gravel to silty sand with gravel 15 to 18 ft: silty sand with low-plastic silt 18 to 20 ft: generally poorly to well-graded sand with 5-10% non-plastic silt, gravel and occasional cobbles

46 Groundwater Elevation, feet Emigrant Trail Monitoring Wells Groundwater Levels upstream middle downstream

47 Updated Preliminary Design Based on Early Predesign Findings Groundwater levels indicate water moving primarily parallel to river Pump test imperative to assess impact of silts

48 Initial Predesign Concepts

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51 Current Implementation Schedule Predesign: Fall 2012 to Fall 2013 Design and Permitting: Fall 2013 to Summer 2014 Construction: Summer/Fall of 2014

52 Project Challenges Challenges DEQ Permitting Continued community acceptance/ endorsement Funding Land use Strategies Continue site characterization & dialogue Develop sound technical information and continued dialogue Pursue federal grants Work closely with County planning

53 Quiz: Question for 1 st Gift What does WMA stand for and what does it mean? Waste Management Area Example of acceptable definition answers: Defines dispersion limit Subsurface area between discharge point and surface water

54 Quiz: Question for 2 nd Gift Name one thing you are trying to achieve with indirect discharge? Improved water quality Control of the land where the WMA is located Discharge reaches surface water No impact on drinking water No impact on groundwater (outside of the WMA)

55 Questions 10/24/