Laserfiche WebLink
Mr. James Diel - 2 - 16 May 2014 <br /> The degradation rate estimate assumes that the flux across two 4 square inch chambers are <br /> representative of the flux rate across the %acre LNAPL footprint, that the areal extent of the <br /> LNAPL mass is reasonably correct, there are not significant seasonal variations, and all the <br /> captured carbon dioxide associated with fossil fuel is from LNAPL degradation. Furthermore, as <br /> Central Valley Water Board staff discussed with Mr. Scott Hackman of Arcadis in our 27 April <br /> 2014 telephone conversation, the entries in Table 2 that enumerate degradation rates do not <br /> follow the methodology presented in the Appendix. <br /> Although the data suggests that the degradation rate is likely to remove greater quantities of <br /> LNAPL than can be removed by bailing, physically bailing of LNAPL enhances the rate of <br /> remediation. However, Central Valley Water Board staff will consider discontinuing bailing if <br /> UPRR can accelerate the biodegradation processes. <br /> Biological degradation only occurs on the surface area of the LNAPL volume. Degradation <br /> waste products, such as methane and carbon dioxide, accumulate at the surface, which limits <br /> biological activity. UPRR could hasten degradation by removing waste gases with a system <br /> such as soil venting or soil vapor extraction, and by stimulating biological degradation by adding <br /> nutrients. If UPRR wishes to discontinue bailing LNAPL from monitoring wells, it should prepare <br /> a work plan for accelerated biodegradation. <br /> Meanwhile, UPRR should continue to bail LNAPL from select monitoring wells quarterly. The <br /> 2013 volume removal data suggests that monitoring well MW-08A is not productive and may be <br /> removed from the bailing schedule. Please continue to provide LNAPL removal volumes in the <br /> se i-annu reports until UPRR implements accelerated biodegradation. <br /> AMY TERRELL, P.E. <br /> Federal and Private Sites Cleanup Unit <br /> cc: Ms. Adrienne Ellsaesser, San Joaquin County Environmental Health Dept., Stockton <br /> Mr. Nuel Henderson, San Joaquin County Environmental Health Dept., Stockton <br /> Mr. Scott Hackman, Arcadis, Roseville <br />