Laserfiche WebLink
1433 North Market Boulevard +Sacramento California 95834-1943 • (916)928-3300• Fax(916)928-3341 <br /> January 29, 1996 <br /> Project 0805-114 02 <br /> Mr Michael Infurna <br /> E E 1 V U <br /> San Joaquin County Public Health Services <br /> Environmental Health Department <br /> P O Box 388 JAN 3 0 1996 <br /> Stockton, California 95201-0388 ENVIRONMENTAL HEALTH <br /> Re Addendum to Problem Assessment Report for ARCO Service Stat><ofn No-' T%C�S <br /> Located at 7906 North EI Dorado Street, Stockton, California <br /> Dear Mr Infurna <br /> At the request of ARCO Products Company (ARCO), EMCON has prepared this <br /> addendum to the problem assessment report (PAR), prepared by RESNA Industries <br /> (RESNA, June 6, 1994) for the subject site (see Figure 1) Based on a letter from San <br /> Joaquin County Public Health Services (SJCPHS) dated August 29, 1994, the county <br /> I <br /> requested an addendum to the PAR be submitted outlining remedial alternatives and further <br /> �1 assessment activities necessary to delineate hydrocarbons north and south of the site <br /> EMCON submitted three access agreement forms to the property owner north of the site and <br /> did not receive a response However, during a meeting conducted on May 16, 1995, between <br /> SJCPHS, ARCO, and EMCON, SJCPHS concluded that the additional monitoring well north <br /> of the site was not necessary at this time Because relatively low concentrations of benzene <br /> have been detected in water samples collected from monitoring well MW-10 (southern most <br /> well) during the last four quarters (highest concentration of 12 parts per billion) and the <br /> hydraulic gradient has been consistently toward the east to southeast, it is EMCON's opinion <br /> that a monitoring well south of monitoring well MW 10 is not warranted at this time <br /> In addition, this report presents the results of a supplemental subsurface investigation The <br /> subsurface investigation consisted of drilling four soil borings and installing two air sparge <br /> wells and two vapor extraction wells The purpose of this investigation was to install <br /> additional remedial facilities to be incorporated into the existing remediation system The <br /> air sparge wells were connected to the air sparge system during the third quarter 1995 <br /> REMEDIAL ALTERNATIVES <br /> Based on the size of the site, the extent and concentrations of the hydrocarbons in the soil and <br /> groundwater, and the type of soil present at the site, in-situ bioremediation, chemical <br /> neutralization, and slurry wall containment are not technically or economically feasible remedial <br /> options The following sections outline additional remedial options <br /> SAC\N\PiW805\08051140 2ES-95\pw 1 <br />