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ORNIA -Environmentr-ction Agency - <br /> NA REGIONAL WATER QUALITY CONTROL BOARD PETE WILSON Govern <br /> AL VALLEY REGION m"> <br /> 3443 Routier Road, Suite A 1 <br /> Sacramento, CA 95827-3098 H` HE <br /> ;fir'- + 'i Al TI/ p' <br /> PHONE: (916) 255-3000 /?Vlu <br /> FAX: (916) 255-3015 Cr C <br /> Ppb ! 24 <br /> 1 February 1996 <br /> Mr. Nick Nickerson <br /> Unocal Corporation <br /> 2000 Crow Canyon Place, Suite 400 <br /> San Ramon, CA 94583 <br /> GROUNDWATER MONITORING. PUREGRO/BREA AG, STOCKTON <br /> Thank you for submitting the Fourth Quarter 1995 Quarterly Monitoring Report for the former <br /> PureGro/Brea Ag facility at 1905 N. Broadway, Stockton. I have several comments after reviewing <br /> the report: <br /> - As you know, nitrate may be expressed either as nitrate or as nitrate-nitrogen; there is a <br /> difference of about 4.5 between these two values. The report is rather confusing in that the <br /> summary analytical table lists nitrate-N, while the cover letter and the text refer to nitrate. In <br /> the future, please use one form or the other throughout the entire report. <br /> - The executive summary section implies that the background nitrate concentration in the <br /> groundwater is about 40 mg/1. This is not quite accurate, as nitrate concentrations in MW-3 <br /> and MW-10 have ranged from 24 to 131 mg/l of nitrate (5.3 to 29 mg/l NO3-N). <br /> - Figure 3 contains a statement that MW-8 data was suspect and wasn't used to calculate the <br /> potentiometric surface. The body of the report should contain a discussion about why this data <br /> was suspect and what will be done in the future to obtain correct elevations from MW-8. <br /> I have also reviewed the file recently, and think that it would be appropriate to meet to discuss our <br /> progress. The topics should include the need to define the extent of the plume, the status of the on- <br /> site remediation, the need for a well installation report, and the on-site soil sampling conducted by <br /> Crop Production Service. <br /> Jan Wagoner and I discussed meeting during the week of 12 February; please contact me to confirm <br /> the date and time. I can be reached at (916) 255-3104. <br /> WENDY WYELS <br /> Ag Regulatory Unit <br /> cc: Mr. Jan Wagoner, Unocal, West Sacramento <br /> Mr. John Rapp, Sierra Pacific Groundwater Consultants, El Dorado Hills <br /> Mr. Mike Infurna, San Joaquin County Public Health, Stockton <br />