Agenda - 01-27-2009 - 4 - Laserfiche WebLink

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2 The observation well network that is now being planned for the County will address these issues as well as others including recent work exploring the relationship between bedrock lithology (geology) and arsenic content in groundwater. The stated goals of the Observation Well Network, consistent with the Water Resources Initiative adopted in 2005, are as follows: A. Monitor impact of drought on groundwater levels across the County, i.e., to work as an "early warning system" and permit monitoring of groundwater quantity county-wide. B. Conduct further delineation of groundwater base flow, which is the contribution of groundwater to streams. This would provide useful information regarding the amount of groundwater which feeds surface water reservoirs in the County. C. Enable further research into groundwater quality issues, including elevated radon and arsenic concentrations detected in groundwater during previous investigations in the county. Elevated radon concentrations were detected by Cunningham and Daniel in their 2001 report entitled Investigation of Ground-Water Availability and Quality in Orange County, North Carolina. This report documented radon activity in groundwater ranging from 38 to 4,462 picoCuries per liter (pCi/L), and a median groundwater concentration of 405 pCi/L in Orange County. The proposed Federal MCL (maximum contaminant level) for radon is 300 pCi/L if no statewide or local EPA approved multimedia mitigation program exists, with an alternative proposed MCL of 4,000 pCi/L if an approved multimedia mitigation program is in place. The 2001 report of Cunningham and Daniel also identified some correlation between bedrock lithology and radon concentration. Arsenic concentrations in groundwater in this area of the Piedmont have been documented by several researchers, and the North Carolina Geological Survey has recently worked to establish links between arsenic concentrations and certain bedrock lithologies in Orange County. A groundwater level measurement program as described above is only possible with a dedicated groundwater observation well network. Periodic sampling of observation wells in identified areas to research radon and arsenic content in groundwater, as well as other groundwater quality issues, will also be possible. Partnerships in the development and utilizations of the network are possible with local Federal and State agencies. Fortunately collaboration with local scientists interested in exploring aspects of groundwater quality and quantity issues in the County is also anticipated as a result of the establishment of the network. In addition, some existing wells on County-owned or leased property appear to be good candidates for the network, thus lowering the over-all cost of the network. Guilford County has an observation well network and Wake County is developing a network for similar reasons. FINANCIAL IMPACT: Funds for this project are included in the CIP for the next three years. Opportunities for partnering with interested State and Federal agencies may also be possible and are being aggressively explored by staff. The amount of funding for the first year of the program is proposed for $35,000 in FY 2009-10 (the program is projected to cost $180,000 over three fiscal years). RECOMMENDATION(S): The Manager recommends the Board receive the presentation concerning the Observation Well Network project and provide feedback and guidance to staff for further refinement of the project plan.