Report PAC09-29

Report to the Policy Advisory Committee (PAC09-29)

Date:               March 5, 2009
To:                   Policy Advisory Committee
From:              Steve Brown, P.E. – Town of Cary, Director of Public Works and Utilities
Prepared By:   Leila Goodwin, P.E. – Town of Cary, Water Resources Manage
Subject:           Alternative Discharge Location to Harris Lake

During early discussions, the Division of Water Quality (DWQ) recommended that the Towns of Cary, Apex, and Morrisville not consider a wastewater discharge into Jordan Lake or to the Cape Fear River upstream of Buckhorn Dam, and that the Town of Holly Springs plan to discontinue their discharge to Utley Creek (a tributary to Harris Lake), due to water quality issues within the Creek.  Based on these DWQ recommendations, the most feasible discharge location for the Western Wake Regional Wastewater Management Facilities (WWRWMF) was determined to be into the Cape Fear River, below Buckhorn Dam. The Partners continued to investigate whether there might be less costly conveyance alternatives with less potential for impacts than the 12-mile effluent pipeline. Recent discussions with DWQ and Progress Energy have indicated that a Harris Lake discharge may be feasible.   

Attachment A, which is posted on the Partners’ web site (www.westernwakepartners.org), presents background information including a map and a brief summary of potential benefits and challenges.  This report presents more a detailed discussion of specific issues as well as a recommendation for continued evaluation.

Preliminary cost evaluations for discharging to Harris Lake instead of to the Cape Fear River indicate that, while conveyance costs would decrease, the treatment costs would increase, which could result in no net change in costs.  However, there are several opportunities to reduce costs for the Harris Lake discharge that depend on the outcome of continued discussions with DWQ and Progress Energy regarding the exact discharge location and permit limits.   The table below summarizes the preliminary estimates of the cost savings or increases related to moving the discharge to Harris Lake.

The Partners’ consultants have developed a water quality model in consultation with DWQ staff (we met with them February 3, 2009), and are preparing a model calibration report for submittal to DWQ along with a request for Speculative Limits.  While discussions with DWQ have generally been positive, the DWQ written response to that request is the next milestone in determining whether an NPDES permit can be obtained for the discharge to Harris Lake.  Preliminary modeling results indicate that a discharge is feasible, with a higher level of treatment than is being required for the Cape Fear River discharge.

The status of water quality modeling tasks is:

• Completed (Dec 07 – Jan 09)
• Development of modeling approach
• Modification of monitoring program
• Development of watershed and lake models
• Draft Model Calibration TM submitted to DWQ
• Evaluation of Model Sensitivity to Discharge
• Preliminary model report
• EMC Water Allocation Committee (WAC) Update on Harris Lake Discharge – Sept. 08
• Receipt of 2008 monitoring data
• Draft update of calibration TM
• Discuss updated calibration with DWQ – February 3, 2009
• Define potential scenarios with Partners, DWQ and Progress Energy
• Update model analyses and reports
• Submit request for speculative limits with Final Report of the Modeling Analysis
• Update the EMC WAC on Harris Lake Discharge – March 11, 2009

(Note: Holly Springs will also be evaluating, separately, the feasibility for their discharge to remain at its current location in Utley Creek, which is a tributary to Harris Lake.)

Discharging treated water from the WWRWMF into Harris Lake offers increased water management options, since the discharge is into a reservoir (similar to Jordan Lake).   There is no such opportunity with the discharge directly to the Cape Fear River – once the water is discharged it flows directly downstream and cannot be stored during wet periods for later use during dry periods. Downstream water users have voiced concerns about the discharge not going directly to the Cape Fear River, because there is currently no minimum release required from Harris Lake.

Under current Harris Lake operating conditions, preliminary modeling results (modeling done by TJCOG using the Cape Fear River Basin Hydrologic Model) show that during some dry periods there would be slightly more water released from the water quality pool of Jordan Lake to meet the low target at Lillington.  However, there would be no appreciable difference in flows at Lillington or Fayetteville with the Harris Lake discharge.  The Partners are working with Progress Energy and the Division of Water Resources (DWR to identify and evaluate potential scenarios for managing flows during drought periods, and will also work with downstream stakeholders to identify and address their specific concerns about flow in the Cape Fear River. 

At the meeting on March 11, 2009, DWR will update the EMC WAC regarding evaluation of potential hydrologic impacts related to the Harris Lake discharge.

Even though water from Harris Lake ultimately flows into the Cape Fear River, the issue of Interbasin Transfer (IBT) from Jordan Lake (Haw River subbasin) to the Cape Fear River subbasin would need to be addressed.  We met with DWR to discuss this on February 12, 2009, and DWR is evaluating how impacts need to be evaluated and what process they would use to address IBT.  At the meeting on March 11, 2009, DWR will update the EMC WAC regarding the process for addressing IBT for a Harris Lake discharge.

The schedule is the biggest unknown factor affecting whether the Harris Lake discharge will continue to be a feasible option.  If either the NPDES permitting or the process for addressing IBT becomes too lengthy, project delays could become unacceptable and the Partners would continue with the currently proposed Cape Fear River discharge.  After permits for a Harris Lake discharge are obtained, construction can be phased such that schedule impacts from design modifications would be minimal.  Schedule impacts can be evaluated in more detail after receiving a Speculative Limits response from DWQ and after DWR defines the process needed for addressing IBT.

The next steps are:

• Submit Speculative Limits request to DWQ with the Final Report of the Modeling Analysis
• Continue to work with DWR to define IBT process and analysis needs for evaluation of hydrologic impacts
• Work with DWQ and DWR to define environmental documentation needs
• Refine evaluation of cost and schedule impacts based on Speculative Limits, required IBT process and environmental documentation needs
• Update PAC on costs and schedule and confirm path forward
• Prepare environmental documentation and permit applications for Harris Lake discharge
• Modify designs for Harris Lake discharge

The Partners’ consultants are currently contracted to do a portion of the work listed above.  An allowance of $200,000 for additional engineering work related to the environmental documentation and permitting has been included in the FY10 budget for Preliminary Work.  A more detailed estimate of additional engineering work required for design modifications will be provided to the PAC for approval before additional design work is undertaken.

The TAC recommends that the PAC approve continuing to move forward with the next steps for a discharge to Harris Lake.

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