ARCHIVED REPORTS_XR0012228 - Laserfiche WebLink

Home Browse Search

' Mr Nuel Henderson Page 2 of 5 The potentiometric surface was above the top of the screened intervals in monitoring wells ' MW4 through MW13B, MW15B, MW15C, MW16B and vapor wells VW1 and VW4 Vapor wells VW2 and VW5 were dry Groundwater flowed in an east-northeasterly direction The average gradient across the site was approximately 0 002 - 0 003 feet per foot A tpotentiometric surface map generated using the groundwater elevation data from all site groundwater monitoring wells is shown on Figure 2 Groundwater monitoring data are summarized in Table 1 Monitoring data sheets and well construction details are included in ' Attachment A On November 19 and 20, 2003, a Ground Zero technician collected groundwater samples from ' monitoring wells MW3 through MW6, MW8, MW 10, MW 11 and MW13B through MW 16B, and sampling groundwater from vapor wells VW4 and VW6 ' A minimum of three well casing volumes was purged from each site well prior to sampling During the purging process, physical parameters (pH, electrical conductivity, and temperature) ' were monitored Subsequent to parameter stabilization, and a minimum of 90% recovery of initial depth to groundwater measurements, groundwater samples were collected and placed in an iced cooler for transport to Argon Laboratories (ELAP #2359) under chain of custody ' protocol Analysis consisted of gasoline oxygenates, EDB and 1,2-DCA by EPA Method 826013, TPHg ' by EPA Method 8015 modified and BTEX by EPA Method 8021B Purge water was transferred into labeled 55-gallon drums approved by the Department of Transportation (DOT) The waste is stored onsite within a secured area Purge logs are included in ' Attachment A ' GROUNDWATER ANALYTICAL RESULTS ' Groundwater Monitoring Wells TPHg was detected in all sampled wells except MW6, MW 10, MW 11, MW 15A through ' MW15C Benzene was detected in all wells sampled except for MW6, MW8, MW 10, MW 11, and MW 15A through MW15C Dissolved TPHg and BTEX levels in the remaining monitoring wells were within historical ranges, and appear to be stable to decreasing TPHg ' and BTEX concentration data are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation MTBE continues to below laboratory method detection limits (MDLs) in wells MW5, MW6, MW8, MW13B and MW15C MTBE was detected in wells MW3 (48,000 parts per billion - ppb), MW4 (8,300 ppb), MW 11 (78 ppb) and MW 14 (82,000 ppb), which are located along ' the southern portion of the site (Figure 2) In downgradient wells MW 15A and MW 15B (Eugenia and Market) MTBE was reported at concentrations of 6 9 ppb and 440 ppb, G 1GR0UNI7=0MQMR\200314gm2003 doc