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03/24/2000 15:03 FAX 530243165 CH2M HILL 0003/004 Sent By: RWO013; ip 2553015; Feb-240 4:07PM; Page 314 Ms. Miriam L. Barbonio Page 2 24 February 2000 Clcatrup goals proposed for groundwater are the Water Quality Objectives for nitrate and ammonia: 10 me nitrate, and 1.5 mg/l ammonia. However, theme is a published taste and odor threshold for ammonia of 0.5 mg/1, so this sho aid be used instead. As I have discussed previously,the primary cleanup goal will be the background concentration for nitrate and ammonia. Side-gradient wells show nitiate as lOw as one mall and ammonia not detected. if Koppel demonstrates that the background concentration cannot be met,then the water quality goal becomes the clearmp goal. The RAP proposes to obtain soil samples initially and at rive year intervals. Eight subsamples will be composited into one sample at each of three depths for each of four separate planting areas. CHUM Hill proposes to analyze each composite sample for nitrate, ammonia and pH. Soil analyses should include. total Kjeldahl nitrogen(TKN). The RAP proposes to reduce monitoring well sampling frequency to semi-annually. As I discussed with Mr.Vogt during our 23 February 2000 telephone conversation,i will review this request in separate eorrespendcace when 1 review the 1999 Annual Report. The RAP also requested eliminating the,groundwater monitoring regWrement for TKN analyses and total dissolved solids(TDS). As the RAP notes,the monitoring record shows that TKN identified on- site consists of ammonia,not organic nitrogen,and the TpS information can be inferred from the electrical conductivity data that is regularly collected during monitoring events. in our 23 February conversation,Mr,Vogt and I agreed that he would proceed as usual with the first quarter monitoring event,excluding the TKN and TDS analyses,and we will both work to implement any changes to the schedule for the second quarter event. The RAP proposes the first evaluation to occur at year direc following initial planting,with subsequent evaluations occuring at year 5, year 10 and year 15, At the first three-year evaluation, CH2M Hill will analyze the impact that the phytoremediation has had on groundwater quality,gild the five-year ovalcations will also include the impact on soil constituents. .in order to insert the initial activities into the retard,please submit a brief letter report sUunman-ring the completion of initial activities. This should include a table of soil sampling results, dates of planting, variety of trees, any deviations from the work plan, and any other details(hat should be in the record. CH2M Hill originally submitted this RAP as a Draft. However,as no other changes are necessary to convert this document to a final,Mr. Vogt provided a replaCcutent cover page that changes the Draft Remedial Action Plan into a Final Remedial Action Plan. The Remedial Action Plan is approved subject to the following conditions: 1. The primary groundwater cleanup goals shall be one mg/1 nitrate and non-detectable ammonia. The nenondary goals$hall be the water quality goals of 10 mgrs nitrate as nitrogen, and 0.5 mg/1 ammonia as nitrogen. 2. Soil analyses shall include TKN in addition to nitrate,ammonia, and pH- According the schedule in the RAP, CH2IM Hill will sample soils on approximately 8 March,weather permitting. A short letter report summarizing the planting activities The shall be duE once r n tly wi he he second quarterly monitoring report which is due 30 July q vqmbined with the tiolinC the fiRhyeaaluanwilbe due 30 Juary W,the ton y ar evaluation will be du 0 January