SITE INFORMATION AND CORRESPONDENCE

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BREA AG - 2 - the total nitrogen in the soils from this site would be found by adding the nitrate and TO values. Kleinfelder concludes that the groundwater beneath the site has been impacted with 1,2- DCP and nitrate, but that the source can not be determined with just the five soil borings. They recommend installing a minimum of three monitoring wells on-site. There is also the concern that this assessment activity not slow up the construction work, because Brea Ag needs to pour the concrete pad before the rains start. A related issue to the Brea Ag work is the contamination by 1,2-DCP of several Stockton drinking wells. As part of the Well Investigation Program, these California Water Service wells were first sampled in 1984, and low levels (to 2.4 ppb) of 1,2-DCP have been found. A Final Report memo was written in 1989; staff's conclusion was that the 1,2-DCP could have come from Brea Ag, but that there was no hard evidence. The Final Report contains information about area geology and groundwater conditions, as well as a listing of nearby wells. I agree with Kleinfelder's proposal to install monitoring wells. I think that at least four wells should be installed because the "Final Report" shows that groundwater flow direction changes radically from year to year. The wells may need to be screened over a large area since groundwater depths also appear to fluctuate. Strong consideration should be given to designing and positioning the wells so that they could be used in a pump-and-treat scenario. If the site is determined to be a source of groundwater contamination, this would be the next logical step for the project. Kleinfelder should i also take into account the information found in the "Final Report" when proposing future strategies. As far as the construction goes, the only soil that is found at hazardous levels is 2 ppm of DDT at the 6' deep level of boring B-3. I propose that we allow Brea Ag to leave the soil in place, and to build the tank farm on top. They may have to put a restriction in their deed about the hazardous waste. I feel that it would be more beneficial to have this concrete cap installed this winter, to reduce any more migration of nitrate and 1,2-DCP into the groundwater, than to do excavation and testing of low levels of DDT. Kleinfelder states in the report that a concret cap "will reduce vertical migration of rain water through the soil profile in the vicinity of the dry wells, thus futher reducing the potential for 1,2-DCP and nitrate to continue downward migration to the ground water surface. The concrete cap over the isolated concentration of DDx will further reduce the potential for vertical migration toward the ground water." I also talked to Wendy Cohen about this investigation tying-in to the Well Investigation Program. She asked that I provide copies of all materials, so she could put it in the appropriate file.