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q <br /> 4 - A.'W' PARTMENT <br /> ENVIRO MENTAL HEALTH <br /> ¢o�,N SAN JOAQUIN COUNTY <br /> Donna K. Heran, R.E.H.S. Unit Supervisors <br /> Director304 East Weber Avenue,Third Floor <br /> Carl Borgman,R.E.H.S. <br /> Laurie A.og Cotulla, R.E.H.S. Stockton,California 95202-2708 Mike Huggins, R.E,H,S., R.D.I. <br /> °,... ..',,:Q • Program Manager <br /> o,R�� Telephone: (209)468-3420 Douglas W.Wilson, R.E.H.S. <br /> Margaret Lagorio,R.E.H.S. <br /> Fax: (209) 464-0138 Robert MCClellon, R.E.KS. <br /> .Tune 22, 2006 Website: www.sjgov.org/ehd/ e1f Carruesco, R.E.H.S. <br /> David Welch CC� C-_j <br /> Neil O. Anderson &Associates, Inc. <br /> 902 Industrial Way <br /> Lodi, California 95240 <br /> RE: Nitrate Loading Study Addendum Dated June 13,2006 by Neil O. Anderson & <br /> Associates (NOA) for 9542 S.Airport Way, Manteca <br /> San Joaquin County Environmental Health Department(EHD)has received and reviewed the <br /> above addendum and has concerns regarding mitigation methods used to alleviate long-term <br /> nitrate loading to groundwater and conclusions drawn based upon the mitigation methods. <br /> NOA calculates the potential buildup of nitrates in groundwater to be 15.7 mg/L-N for Parcel 1 <br /> (commercial use)and 18.9 mg/L-N for Parcel l (residential use). These nitrate levels exceed the <br /> Maximum Contaminant Level(MCL) for nitrate in drinking water which is I Omg/L-N. NOA <br /> recommends a modified.filter bed septic system for each parcel, with four inches of loose <br /> compost or peat at the base of the filter bed and oversized septic tank(s), to help mitigated nitrate <br /> loading concerns. It is noted in the report that a ten percent reduction in loading could be <br /> achieved using these mitigations. Assuming a ten percent reduction in nitrate loading, the revised <br /> nitrate loading values would be 14.1mg/L-N for Parcel 1 and 17mg/L-N for Parcel 2. These <br /> revised values still exceed the MCL for nitrate of 10 mg/L-N. <br /> Based upon the revised nitrate loading values, it would appear additional mitigation measures are <br /> required to reduce the nitrate loading for both parcels to 10 mg/L-N or less. EHD requests that <br /> the addendum be revised to address alternate technology such as engineer designed small <br /> wastewater treatment systems for removal of total nitrogen in the wastewater in commercial <br /> system. NOTE: Parcel,#2 may not meet requirements for habitable structure due to size and <br /> nitrate loading calculations as performed. <br /> r . <br /> I <br /> If you have any questions, please contact Greg Oliveira, Lead Senior Registered Environmental <br /> Health Specialist, of my staff at(209)468-3854. <br /> Donna HHerraan, R.E.H.S., Director <br /> Mike Huggins, Supervising R.E.H.S., R.D.I., Program Coordinator <br /> Environmental Health Department <br /> r <br /> MH: tl <br /> cc: Yasir Khanshali, Property Owner <br />