Laserfiche WebLink
€mcon <br /> ' <br /> 1433 North Market BoulevardSdcrameri#o`„Cv]isor9. _.- I 1 11 `�8gA-1943 . (916)928-3300• Fax(916)928-3341 <br /> 1 <br /> December 21, 1995 <br /> Project F90-002.04 <br /> Ms. Linda Turkatte <br /> San Joaquin County Public Health Services <br /> PO Box 388 <br /> Stockton, California 95201-0388 <br /> Re: Review of Remedial Action at A. T eichert& Son, Inc., Facility, Located at <br /> 103 North E Street, Stockton, California <br /> Dear Ms. Turkatte: <br /> This letter summarizes the results of long-term groundwater monitoring data at the <br /> A. Teichert & Son facility located at 103 North E Street, Stockton, California. In addition, <br /> it provides EMCON's opinion on an alternate treatment option at this point in the cleanup <br /> process. <br /> Quarterly groundwater data collected since April 1990 indicate that the long-term trend for <br /> hydrocarbon concentrations is going down. If total petroleum hydrocarbons as gasoline <br /> (TPHG) and total benzene, toluene, ethylbenzene, and xylenes (BTEX) contours were to <br /> be plotted out every quarter, they would indicate a shrinking plume. A shrinking plume is <br /> the optimum plume configuration for the implementation of intrinsic bioremediation. A <br /> bacterial plate count for total heterotrophic bacteria suggests that biodegradation is <br /> ongoing at this site. The bacteria plate count of 13,000 colony forming units per milliliter <br /> (cfu/ml) represents a significant microbial population. Indigenous populations of over <br /> 10,000 colony forming units per milligram (cfu/mg) in soils is sufficient for bioremediation. <br /> Typically, populadol,s in groundwater are correspondingly louver. <br /> To expediate the natural attenuation process, biostimulation in the form of oxygen delivery <br /> and nutrient application, can be performed at this site. Air sparging at low pressures and <br /> flow rates, sometimes called biosparging, can be utilized to provide oxygen for the <br /> microbes. A typical range for the injection pressure is 3 to 10 psi (depending on hydrostatic <br /> head), whereas a typical flow range is approximately 1 to 3 cubic feet per minute (cfm). <br /> Studies and experience have shown that at these low pressures and flowrates, vaporization <br /> and migration of hydrocarbon vapors is not a problem. A dissolved oxygen (DO) analyses <br /> conducted on November 13, 1995,recorded sufficient levels of oxygen in the aquifer, with <br /> levels ranging from 8.0 to 9.2 milligrams per liter. <br /> 3ACV 0F90D020.4ES-95*pt:2 <br />