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E Advanced GeoEnvironmental, Inc . 05 December 2005 AGE-NC Project No. 95-0184 Ms. Vicki McCartney San Joaquin County Environmental Health Department t 2 -t l-OS- 304 East Weber Avenue, 3rd Floor Stockton, CA 95201 Subject: Ground Water Monitoring Schedule LARRY'S AUTO REPAIR 308 North Grant Street, Stockton, California Dear Mr. McCartney: Advanced GeoEnvironmental,Inc. (AGE)has prepared this ground water monitoring schedule for the well network at the above referenced site,on behalf of the property owner Mr.Charles Skobrak. The scope of work generally for quarterly ground water monitoring included the recording water level measurements, checking for the total depth of the wells and collection of ground water samples. As stated in previous reports, procedures used for the sampling of the monitoring wells were described in the AGE-prepared Work Plan Addendum, dated 15 December 1995. The work plan details the installation of wells and sampling of only monitoring wells "Using a dedicated bailer or submersible pump, surge and purge each monitoring well."AGE has sampled the vapor wells most likely at the request of the San Joaquin County Environmental Health Deartment. - n.q +I +Jte pRst, S0J+17,a-k/GST tA7l%r'1 • In the past eight years, the general scope of ork included the monitoring of wells MW-2 through MW-4, MW-7, VW-2B, VW-3, -4, VW-5B and VW-5C. The VW wells are surroun ,t y wells MW-1 through MW-3. The top of the screen intervals of the VW wells ra�es from 33`'feet to 45 feet bsg, exce t for well VW-5B which has a top of screen at 26,feet bsg. With the typical top of the>` onitoring we creens at 55 feet bsg.- -Frao rw ?• • The soil type exposed to the VW wells is fine grained and mostly impacted with hydrocarbons, moreoverrthe soil type exposed to the(W we1fss`has demonstrated to be coarse grained. The significant and recurring ingease of theground water suff4ce into the VW wells over the past years from a depth ofSsfeet bsg during installatio>o o�30 feet bsg at the highest ground water level has caused almost all the wells on the site to become drowned and further desorbed hydrocarbon$contamination from the soil into the YW wells. The contamination detected in sample collected from the VW wells is most likely influenced ;'he impacted soil,as these wells were proposed as soil vapor wells not monitoring wells hile the contamination detected in sample collected from the VMW wells represents the mayor water bearing unit across the site. • Chemical and depth to water data collected from the N/ lew l�has remained stable the past years, which is also true for the� wclls-detnonstrating exceptionally high- concentrations of dissolved hydrocarbons, with a very stable average concentration. The typical concentration for total petroleum hydrocarbons detected in the.VW wells has been ,,',7 Shaw Ro id, Stockton,Calitomia 95115 'I'elephone(209)469-1006 Fax (309)467-1118