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. In our opinion, the distribution of contaminants (Detail B) indicate that spillage and <br /> leakage was absorbed to a large degree by the clayey sediments in the vicinity of the <br /> former tank location The excavation appears to have effectively removed a large <br /> portion of the contaminant mass, and the residual contaminants (Detail C) comprise <br /> only about 0 003% of the initially calculated contaminant mass estimate <br /> Conclusions and Recommendations <br /> Soil excavation and exploratory borings were used to ascertain the extent of petroleum <br /> contaminants in the vicinity of former underground storage tank locations An <br /> excavation was advanced to 10- to 12-feet where chemical testing indicated the limit of <br /> contaminants The contaminant sources have been removed and 505 tons of contaminated <br /> soil was properly disposed off-site Limited residual concentrations remain, and these <br /> are anticipated to decline through natural biodegradation processes <br /> In our opinion, further excavation and subsurface definition work is not warranted at <br /> this time Since groundwater monitoring data shows that contaminants have not been <br /> detected in wells since 1993, additional groundwater monitoring is not warranted <br /> WRIGHT proposes that this site be considered a candidate for site closure by PHS-EHD at <br /> this time Upon receipt of site closure approval, WRIGHT proposes that the existing <br /> groundwater monitoring wells be properly abandoned <br /> Limitations <br /> This report has been prepared for the specifically for the Old Bus Facility at 315 East <br /> 11 th Street site, and was done according to the State and local agency suggested guidance <br /> documents for these investigations The interpretations, conclusions and <br /> recommendations made herein are based on the data and analysis for the soil and water <br /> samples collected on-site and should be reviewed in the context of the whole report <br /> Please note that reports of contamination must be submitted to the agencies in a timely <br /> manner Wright Environmental Services, Inc is not responsible for errors I n <br /> laboratory analysis and reporting, nor for information withheld during the course of the <br /> study, and no warranty or guarantee is expressed or implied therein Please call if you <br /> have any questions <br /> Sincerely, �co��'�,� <br /> Wright Environmental Services, Inc �C� �S� ;91� <br /> CERTIFIED <br /> John Lynch Christopher M Palmer ENGINEERING <br /> President C E G 1262 �t'J GEOLOGIST `P <br /> attachments: Figure 1 Site Plan and Geologic Sections <br /> OF cauF <br /> Chemical Analytical Reports and Chains-of-Custody <br />. Appendix A Mass Balance Calculations Sheet <br /> Backfill Bills of Lading <br /> Page 4 <br />