Background:
The City of Ashland owns and operates a wastewater treatment facility within the City limits that discharges to Ashland Creek, just upstream from the confluence with Bear Creek. The wastewater treatment plant is an oxidation ditch plant with a design capacity average of 2.35 MGD and is currently operating at an average of 2.2 MGD. The Department of Environmental Quality National Pollutant Discharge Elimination System (NPDES) permit is divided into two permitting seasons, wet and dry, with different waste discharge requirements in each season. In the dry season, alum dosages followed by membrane filtration of the secondary effluent is implemented to lower total phosphorus concentrations to meet Total Maximum Daily Loads (TMDL) requirements in Bear Creek. This plant and all of the process modifications are relatively new as construction began in September 1998 and was completed in May 2002.
The City submitted a Wastewater Treatment Plant Temperature Management Plan (TMP) to DEQ in April 2002, and two of the temperature management measures outlined in the TMP have been adopted and are specifically required in the current NPDES Permit:
MP-1: The City will develop a market evaluation and water recycling plan. The planning process will include public education regarding the water quality of Ashland's effluent, a market survey, opportunities to increase stream flow by offsetting irrigation demand, and the development of infrastructure needs and costs to meet existing and future demand for recycled water.
MP-4: The City will develop and implement a riparian corridor improvement plan for Ashland Creek. The plan would include temperature modeling to predict the benefits of modifying the riparian corridor, identification of stream reaches that need improvement, and the development of effective and needed modifications. In addition to improving temperature, the planning would focus on improving both in-stream and riparian habitat, reduce flooding, and improving aesthetics.
The City advertised for engineers to:
| 1. |
Review the existing treatment plant NPDES permit and Oregon's new temperature standard identifying permitting and policy issues and summarize the intent of the thermal load limits. |
| 2. |
Review the existing thermal load data and collect additional thermal load data for the treatment plant as required by the wastewater treatment plant NPDES permit. Include explanation of potential additional data requirements and an evaluation of the time required for City staff to collect necessary data. |
| 3. |
Review existing stream flow data and collect additional stream flow data as required by the wastewater treatment plant NPDES permit. Include explanation of potential additional data requirements and an evaluation of the time required for City staff to collect necessary data. |
| 4. |
Evaluate options to reduce thermal load and stream temperature impacts on Ashland Creek. Options should include combined thermal load/ water quality trading alternatives; evaluate options and develop marketing analysis for potential use on adjacent properties. |
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a. |
Evaluate options and develop an implementation plan for riparian corridor improvements to lower existing thermal loads to Ashland and Bear Creeks; |
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b. |
Evaluate the potential for subsurface or hyporheic discharge, geothermal (buried pipe) cooling techniques, or other optimal thermal credit trading options; |
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c. |
Develop a public education component about the water quality of Ashland's effluent; |
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d. |
Develop temperature modeling to analyze and predict the benefits of riparian corridor improvements to lower existing thermal loads to Ashland and Bear Creeks as required by the wastewater treatment plant NPDES permit. |
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e. |
Provide conceptual level costs to implement each option, including an evaluation of options for grant funding or other fees to reimburse the implementation costs; |
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f. |
Define the pros and cons of each option. |
| 5. |
Develop and detail a preferred plan for thermal load reduction to the Ashland/ Bear Creek corridor as a result of the wastewater treatment plant or combined thermal load/ water quality trading options; provide detailed costs for implementing the preferred plan. |
| 6. |
Complete the evaluation of thermal load benefits based on implementation of the preferred plan. |
| 7. |
Discuss options with staff and a final report will be presented to the City Council to provide recommended solution to the thermal loads. |
On March 11, 2005 proposals were received from two engineering firms; Kenndy/Jenks Engineering and Carollo Engineers. An in-house team reviewed the proposals and based upon the firms experience, approach and personal, recommended that Carollo Engineers be awarded the contract to perform this work.
The attached contract and revised scope of work has been accepted by Carollo and City staff. |
