|
Stockton Terminals Technic*ommittee - 2 - • 14 June 2007
<br /> Annual Report, A zone wells AR/MW-1A, AR/MW-9A, AR/MW-23A, TS-4, and TS/M-2 had a
<br /> separate phase hydrocarbon (SPH) sheen. The SPH in these wells is typically measured in
<br /> fractions of a foot. Consistent with historical observations, no B, C, and D zone wells
<br /> contained SPH.
<br /> The highest COC concentrations within each zone during 2006 are tabulated below.
<br /> Groundwater Zones
<br /> A B C D
<br /> cOcs Maximum concentration (Ng/L)/Well ID
<br /> TPI-Ig 100,000/AR/MW-8A 23,000/TO/WC-2B 4,000/TS/MW-1C 9,200/TS/MW-2D
<br /> TPHd 120,000/TOIR-2 7,100/TO/WC-2B 1,700/ARIMW-11C 2,900/TS/MW-2D
<br /> benzene 18,000/AR/MW-8A 11;000/TO/WC-26 1,600/TS/MW-1C 4,400/TS/MW-2D
<br /> toluene 14,000/AR/MW-8A 120/AR/MW-11B 22/AR/MW-11C 331TS/MW-2D
<br /> eth (benzene 3,000/AR/MW-8A 27/TO/WC-213 3.7/AR/MW-14C 67TS/MW-2D
<br /> Total xylenes 16,000/AR/MW-8A 110/AR/MW-11B 23/AR/MW-11C 95/TS/MW-2D
<br /> MTBE 40,000/ARIMW-50 2,800/AR/MW-8B 230/AR/MW-11C 19 TS/MW-2D
<br /> TBA 11,000IMWWA 2,300/ARIMW-11A 1,200/AR/MW-11C 1,600 TS/MW-2D
<br /> TAME 380/AR/MW-50 ND 0.56/ARIMW-5C ND
<br /> The First QMR reports that, consistent with previous results, the A and B zones showed
<br /> localized water table mounding at well PS/WC-1 S/M with radial inward flow at well SP/WC-
<br /> 1 S/M, with gradients ranging from about 0.004.foot per foot (ft/ft) to 0.031 ft/ft. During
<br /> January, groundwater was about one foot shallower than the previous quarter with DTW
<br /> measurements ranging from 2 to 11 feet bgs. The groundwater elevations calculated for the
<br /> Site in January 2007 were about 3 feet lower than typical historical January levels. This may
<br /> be attributable to January 2007 being one of the driest on record for the Stockton area.
<br /> Precipitation amounts in Stockton in January generally average 2.71 inches. However,
<br /> Stockton received only 0.5 inches of rain in January 20071. In the lower C and D zones,
<br /> groundwater flow was generally to the east at gradients ranging from 0.002 to 0.0035 ft/ft. The
<br /> direction of the vertical gradient at the Site was predominantly downwards between the four
<br /> hydrostratigraphic units. During the first quarter of 2007 the downward vertical gradients
<br /> ranged from 0.760 ft/ft between the B and C zones to 0.00 ft/ft.
<br /> Consistent with historical results, TPHd had the highest concentration of all CDCs. The
<br /> highest COC concentrations were detected in the A zone. Maximum concentrations included
<br /> TPI-Ig and TPHd at 85,000 pg/L and 69,000 pg/L, respectively. The highest BTEX detections
<br /> were 9,900 Ng/L, 14,000 pg/L, 2,500 Ng/L, and 1,400 pg/L, respectively. MTBE, TAME, and
<br /> TBA were detected at 29,000 pg/L, 330 pg/L and 3,500 pg/L, respectively. Maximum D zone
<br /> COC concentrations generally exceeded the highest C zone concentrations.
<br /> An Ozone Sparge (OS) system began operation in the Fall of 2004 to address groundwater
<br /> pollution migrating downgradient from the Site. The system is comprised of 57 A zone and 16
<br /> http://www.weatherunderground.com/history/airport/KSCK/2007/l/31/Dai]yH istory.html?req_city=NA&req_state=NA&
<br /> req_statename=NA
<br />
|