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'F ' 20 November 2003 AGE-NC Project No.- 960263 Page 6 of-11 impactedground water is-approxirnately;180;400 and 32'9,000'gallons, respectively.,Based:on-the,. average concentration!.of-.TPH-g and MTBE, n samples collected from on site groundwater monitoring wells`during Ih.c most recent quarterly monitoring event,'the impacted ground water plume contains approximately.l8.2 pounds of TPH-g and 21.3 pounds of MTBE..Vol `utne/mass - = calculation s are in Appendix D. Areas .used-for the vaIuine/mass calculations are illustrated in ' Figures 10-and 11•. - t r 7.0. RECOMM_ ENDATIONS FOR SOIL AND:GROUND WATER-REM_ EDIAT�ION - In January 2002, AGE proposed conduefing aground--water extractlon-`(GWE) feasibility'test-to i determine the effectiveness of this technique to address impacted ground water-at the.'site.However, based on data collected during a similar GWE�test at the,property located approximately�3.00 feet. -� '_ southeast of the site (2450 Toste Road), ,AGE.feels that ground water extraction would not be a feasible remediation alternative.AGE bases-this assumption:on the similar.lithology at thetwo sites: Therefore,AGE proposes installation of a_n in situ-ozone sparging(IOS)system to address petroleum hydrocarbon-impacted soil and ground water at the site.. addition, AGE pro poses evaluating t natural attenuation of hydrocarbons as a remedial alternative for soil above the saturated.zone-.AGE + w' valuate the feasibili -ofnatural attenuation based on" h siochemical/microbiolo ical anal sis' _ will ty _p Y g Y. of soil samples collected during ozone sparge well installation.A RAWP addendumjwill�be prepared presenting the.findings and recommendations for impacted soil not addressed by the IOS sys7.tem. . 7.1.. IOS FEASIBILITY y's s. = An ozone:sparging pilot test has not been perforriied at.the site. Data from soil samples collected at the site indicate that poorly graded sands, silty-gravels--and`silty sands are present iii the shallow = j water bearing zone:and poorlygraded sand.and-silty.sand in the deeper water bearing-zone impacted . '. with MTBE. Soils of this nature typically possess hydraulic conductivity values that:are favorable for air sparging and ozone-injection via air-sparging.Due to the readily higher,vapor pressure of MTBE,low Henry°s Law Constant and MTBE's higher aqueous solubility or the tendency to remain dissolved, the in-situ treatment should be an effective remedial alternative. The ozone sparge system is an in-situ air stripping and;oxidation process-utilizing fine bubbles of ._ _ - ozone injected into saturated soil to extract-and decompose 'dissolved petroleum'hydrocarbon t constituents. Arf ozone generator is utilized tomproduce gaseous ozone which is.injected into the ' subsurface via icrosparge points or fine well screens: The "microbubbles",(approximately 50 3,. micrometers) are.forced out into the surroundingsaturatedsoil and react with the=target analytes, ' =� producing carbon dioxide and water. The frequency and duration of ozone injection periods can be . p g _ - . � regulated at the ozone generator control box:Initially, operation of.the.ozone injection systerii'willti _ e Advanced.GcoEMironmentaf,Inc. L