SITE INFORMATION AND CORRESPONDENCE

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WESTERN 1386 EAST BEAMER STREET WOODLAND CA 95776-6003 uG GEO-ENGINEERS (530) 668-5300, FAX(530)662-0273 REGISTERED GEOLOGISTS wege@caLnet I Ms. Lisa Medina July 16,2012 Leaking Underground Fuel Storage Tank Program San Joaquin County Public Health Environmental Health Division (PHS-EHD) 600 East Main Street Stockton, CA. 95202 (209)468-3455 RE: Amended Work plan for Site Restoration, destruction of excavation well MW10 at former Sanchez property located at 1876 Country Club Blvd., Stockton, California 95203. Dear Ms. Medina: INTRODUCTION The work plan to destroy the wells associated with.this site was approved in correspondence from Mr. Michael lnfurna on February 6, 2012, with modification to the destruction of the excavation well :MW10, which was originally proposed to be pressure grouted, due the installation of the well into the pea gravel backfill of the excavation area. Mr. Infurna along with Mr. Nuel Henderson determined that the well need to be over drilled, by first setting conductor casing or sonic casing over the well to the 28 foot depth, drill out the well to the 28 foot depth, pressure grout the bottom 24 -- 28 foot depth, place pea gravel backfill as the conductor or sonic piping is removed. Remove the surface vault and place compacted road base to within 4 inches of surface and seal the surface with asphalt. Only two drilling contractors contacted can perform the conductor and/or sonic placement to drill out the welt contents. Both contractors estimated the cost for destroying MW 10 over $6,000.00 and an entire day, which does not include Western Geo-Engineers time for supervision and health and safety. The budget to destroy the wells and restore the site was presented to the UST fund in May of 2011 for the fiscal year 2011/2012 and did not anticipate the placement of conductor casing and drill out of the well. A seemingly more cost effective and adequate method of destroying MW10 is proposed. To not use conductor casing or sonic over drill and to over drill the well (not disturbing the pea gravel) with 10 inch hollow stein augers. Once total well depth of 28 feet has been accomplished to utilize the augers and tremie pipe. Fill the augers from bottom of the boring while slowly staging the augers out with 3 sack mix of neat cement. Allow the cement to cure over night and if necessary add more cement as needed. Place a cement plug flush with the vault floor. Remove the 3 foot by 3 foot by 3 foot deep well vault and compact backfill with clean road base to 4 inches of the surface I