SITE INFORMATION AND CORRESPONDENCE

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ADDITIONAL ASSESSMENT WORKPLAN COLBERG BOAT WORKS APRIL 2001 The results of the investigation were documented in Apex's report titled Results of Subsurface Investigation dated August 21, 1997. Colberg has been monitored quarterly for petroleum. hydrocarbon constituents in the groundwater since July'1997. In September 1998, Apex submitted a remediation plan entitled Workplan for Pilot Test and Feasibility Analysis for removal of Hydrocarbons from groundwater. An Addendum to Workplan for Pilot Testing and Feasibility Analysis was resubmitted in January 1999. Prior to acceptance of the remediation s plan,the Co��unty requested a mass balance calculation to determine whether remediation was necessary. Iu April 1999, Apex submitted a report entitled Mass Balance for Remaining T'PH G. p � P Upon review,of the report, the County determined that the extent of contamination had not been `delineated east of MW-3. Based on the response of the County, Apex submitted a Workplan for Additional Subsurface Investigation and Site Characterization1999 dated June 9, 1999. On September 29, Apex I personnel izniplemented the Workplan and installed five geoprobes at the site to establish the 1 'extent of petroleum impacted groundwater east of monitoring well MW-3. The data obtained 1.from the investigation was incorporated into a report entitled Estimated Mass of Petroleum 'Hydrocarbon Constituents Remaining in Groundwater, and submitted to the County on February 2000. ,GHH assumed consulting responsibility for the site in May 2000. The County responded to the lFebruary 2000 Apex report in February 2001 by requesting additional soil and groundwater 'investigation east of MW-3 and soil boring SB-21 as shown on Figure 2. The County letter is :included in Appendix A. i GObjective of ;im acted ound Y The objective of this Workplan is to present a scope of work which will evaluate the extent s water where it is currentl undefined on the eastern portion of the site. This ;Workplan addresses the areas of concern with a screening investigation consisting of six 4eoprobes to approximately 15-feet below ground surface (bgs). f�Soil and groundwater samples collected during the geoprobe investigation will be analyzed to E `1Aetermine the amount of hydrocarbons and oxygenates present at the site. Samples will be 'analyzed for;the presence of total petroleum hydrocarbons as gasoline (TPH G); benzene, toluene Methylbenzene, and xylenes (BTEX); 1,2-dichloroethane 1,2 (DCA); ethyl dibromide (EDS);and j oxygenated fuel additives including methyl-tertiary-butyl-ether (MTBE),D1PE, ETBE, TAME and TBA using EPA Methods 8015 Modified, 8020, and 8254B, respectively. Upon review and analyses of the screening investigation results, one to two additional k` groundwater monitoring wells may be installed to define the extent of impacted groundwater to , the east of MW-3 and provide repeatable sampling data points. ii 2 it �I