ARCHIVED REPORTS XR0012610 - Laserfiche WebLink

Home Browse Search

.� �a_ sa .i arm` ^.r.4E' "� d,_#�. R tiYir..ci�ixrr� �r .� 2iz� - f^.,.- ttSin�'�C' Cpd ifs'' : : ' �€ s, ;r. i},dy �e yt -r w rdeSO'- _13 7 ys.. -tea Cd` �N�E.Y 4',yf 1(tV �T4 :,1. � rJ^ .. a4TYdf` t 4mt' •dl ryN'.K 1 ;y >h t, 4Sr ;, 'r ., ,,t,�.sn.. Yi.,•Yr .LS �r` r' .YI,CIrSllil'^i '�a '..:'�1 ;�u'an`rr'::+�•r; x�vi"i.7��".:it.�t "ii1`:7.. 1�f..2'biJ REGAL 603 B/16/91 2.0 GROUND WATER 2.1 REGIONAL AND LOCAL GROUND WATER FLOW Ground water flow direction in this region is to the west and towards south Stockton from the foothills of the Sierra Nevada Mountain Ranges, and towards the east from the Sacramento-San Joaquin Delta. At present, encroachment of saline waters from the Delta is impairing the qualit'.y o€ the ground water in the Stockton area. WEGE surveyed each well (top of casing) with a transit using the southwest corner of the current tank pad (see Fi— re 3A) as the datum. Survey readings were recalculated to corrF!-�t elevations to the USGS topographic map (USGS East Stockton Qaad. , Figure 2) . Based upon ground water elevation measurements obtained thoughout the evaluation of this site, the overall local flow direction is to the east--northeast at a relatively flat slope. Measurements obtained on March 29, 1991, (Figure 4A) , show a flow direction to the northeast, with a depression at monitor well MW3. Lawrence Tank Testing (LLT) , earlier that week, using their vacuum lift pump, redeveloped monitor wells MW1, MW3 and MW10 in preparation for ground water treatment and vapor extraction. All recovered ground water and sediment was placed into the 1000 gallon "ConVault" located in the treatment compound at the site. on Oune 27, 1991, depth to ground water was measured from top of casing in all of the wells prior to '�he required quarterly ground water sampling. The flow direc-ion was established to the north and east with a ridge forming in the slower velocity sediments from MW10 towards MW2. These measurements occurred approximately early May and one month after the rains of late April and indicates a discharge cycle, see Figure 4B. 2,2 GROUND WATER QUARTERLY SAMPLING AND PROCEDURES Ground water samples have been collected on 4/04/89, 8/24/89, 1/12/90, 5/25/90, 11/27/90, 3/29/91 and 6/27/91. These samples were collected by a WEGE geologist and "Chain of Custody" hand delivered on ice to a state certified testing laboratory (McLaren Analytical or Chemtech Analytical Laboratories) for chemical analyses. These samples were analyzed for fiPH, and BTEii concentrations using EPA Methods 8015 and 602 respectively. Since diesel has never shown up in the sample results, the samples obtained from 11/27/90 and later were analyzed using EPA methods 5031) and 602 for Tital Fuel Hydrocarbons and BTER, see Append'x A. Complete chemical results are presented in Table 1 of this re ort. PAGE 4