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I~S~C Fax:?047951564 3an 18 2000 15:55 P. 02 January 7, 2000 Mr. Jay Shire Wate~ and Sewer Authority of Cabarrus County (WSACC) Rocky River Treatment Facility 6~,00 Breezy Lane Concord, NC 28025 Evaluation of Water Quality Impa~ts from Colonial Pipeline Pump Station Proposal for Environmental Consulting Services Dear Mr. Shive: hDR Per your requ~t, HDR Engineering, Inc. of the Carolinas (FLDR) is submitting a proposal to perform environmental consulting s~rvi~.s related to the docurn~nted release of petroleum constituents at the Colonial Pipeline Company (Colonial) pumping station located near Emerson Branch in Cabarms County, North Carolina. The s~ryices described herein are based on our meeting at th~ Colonial pump station, and subsequent related discusS!OhS. Project Understanding A release of an unknown quantity of pel~-oleum product (gasoline)_oocurred at the Colonial substation between 1991 and 1993. {2olonial retained the services of Hanclex~ to a~sess tho extent of thc and to implement appropriate corrective measures in accordance with North Carolina Department of Environment and Natural Resources (NCDENR) ground-water regulations. An assessmtm r~port addressing the extent of impact was submitted to NCDtiN'R in 1995 with a Corrective Action Plan (CAP) outlining corrective measures submitted in late 1997. Peh'oleum-impacted soils in the vicinity of the release were reportedly excavated and the cause oft. he release remedied. The focus of this project relates to the detection of pelroleum compounds (methyl tertiary-butyl ether) in a recently installed private drinking water well located downgradiem of the substation. Prior to putting the well in service, this resi~ntlal well was sampled by Handex® to determine the presence or absence of pelxoleum compounds. Tho well was reportedly completed within fractured bedrock at a depth of 105 f~t below land surface. Substantial ground-water production was reported from a fraeraro zone at a d~p~h of 75 to 80 fce, t'b~Iow land surface. Tho initial sampling results indicated the presence of approximately 116 parts per billion (ppb) of methyl ethyl.butyl ether (MTBE). HDR's initial opinion is that there is no inmmdiat~ threat to tho Coddle C:~ek Res~rvolr. Thc combination of dilution, disl~rsion, volatilization, and tho air sparging system appears to bo satisfactory for the 'r~moval of MTBE from tho uppermost aquifer. However, the deep, fractured aquifer has be. ch affected by the release of petroleum preducts from the substation, and this deep aquifer is the primary source of drinking water for thos~ residents with private wells in the area; additionally, the full extent and significance of the eontaminatlon is not yet clear. Consequently, HDR concurs with WSACC that Ss issue requires further evaluation. Project $colae In order to provide an iltitial level of determination regarding what threats there may be to huma~ health and the environment,, in¢lading the rese~oir, rela~.d to the above issue, HDR ~roposes to provide the following services to WSACC: ' · HDR Engineering. IRK:;. the C,~olin~ L~rnpl~y~a. own~d Su~ 1400 Telephone 128 S. Trlton S;ree~ 7o4 Charlo~, North Camllna Fax 282025001 ?04 3386760