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0827/2002 11 3B 2094603433 FIFTH FLOOR PAGE 92 <br /> r sm MIN '�N" <br /> I WAWNN E TAL lfMTH OWMIMM <br /> W4 EWMMAVE THM FLOOR <br /> $TOCKM CA l11490 <br /> 0I <br /> ' Approvaad <br /> r3 Appentred with dwMW. Ses ReMSft <br /> ,I Disapproved. Ste Rpmada <br /> �erttatks <br /> )ate By <br /> Approval eAends only to ich ii aflltllARi and dawrffllsd <br /> herean and does not autftodi -4 app[ws any of ardInabOm c <br /> '�"1rE�TY�r" ` "^�•�•• �'"3yff'ears or local ordinances <br /> international Incorporated <br /> August 15, 42 nECE#VED <br /> Project 77T0O [f� {43870 00 0106 �" <br /> Iver 1�&chaelInfurna AUG ? 4 Z00 <br /> San Joaquin County Public Health Services Z <br /> Environmental Health Division EfVVIRUjVMEldTHEALTH <br /> 304 East Webber Avenue,Third Floor PERMIT/SERVICES <br /> Stockton,CA 95202 <br /> Re_ Addendum 92 to Work Plan for Additional Off-Site Assessment <br /> Circle K Store#1205 <br /> 16470 Cambridge Street <br /> Lathrop,California <br /> Dear Mr Infurna <br /> This letter,prepared by SECOR International Incorporated(SECOR)on behalf of Tosco <br /> Corporation(Tosco),a subsidiary of Phillips Petroleum Company,provides an <br /> addendum to the work plan far off-site groundwater investigation in the vicinity of the <br /> subject site(Figures 1 and 2) The purpose of this work plan addendum is to document <br /> a change in the construction of the proposed off-site wells <br /> PROPOSED SCOPE OF WORK <br /> As proposed in SECOR's Addendum to Work Plan For Additional Off-Slue Assessment <br /> dated July 16,2002,which was approved by STEHD on July 19,2002,six groundwater <br /> monitoring wells(MW-10 through MW-15)will be installed at the locations shown on <br /> Figure 2 <br /> PROPOSED WELL CONSTRUCTION MODIFICATIONS <br /> As stated in the work plan above,soil borings will be drilled using 8-inch diameter <br /> hollow-stem auger Upon completion of drilling,a 2-inch diameter groundwater <br /> monitoring well will be installed in each boring Groundwater is anticipated at a depth <br /> of approximately 10-12 feet below ground surface(bgs) The wells will be screened <br /> from approximately 5 feet below ground surface to 10 feet below where groundwater is <br /> first encountexed <br /> Contrary to the well construction details proposed in the field procedures for <br /> groundwater monitoring well installations provided in Attachment B of the July 16, <br /> t 2002 work plan addendum,the wells will be constructed with a sand pack extending <br /> approximately 1 foot above the top of the screen(approximately 5 feet bgs),followed <br /> by a 2-foot bentonite scat The monitoring wells will then be completed with neat <br /> Cement to ground surface The revised field procedures are included as Attachment A <br />