Because a water sample collected from a well is an integration of water from different depths along the well screen, measured concentrations can be biased if analyte concentrations are not uniform along the length of the well screen. The resulting concentration in the sample, therefore, is a function of variations in well‐screen inflow rate and analyte concentration with depth. A multiport sampler with seven short screened intervals was designed and used to investigate small‐scale vertical variations in water chemistry and aquifer hydraulic conductivity in ground water contaminated by leaded gasoline at Galloway Township, Atlantic County, New Jersey. The multiport samplers were used to collect independent samples from seven intervals within the screened zone that were flow‐rate weighted and integrated to simulate a 5‐foot‐long, 2.375‐inch‐outside‐diameter conventional wire‐wound screen. The integrations of the results of analyses of samples collected from two multiport samplers showed that a conventional 5‐foot‐long well screen would integrate contaminant concentrations over its length and resulted in an apparent contaminant concentration that was as little as 28 percent of the maximum concentration observed in the multiport sampler.
A water-quality reconnaissance of surface water and shallow ground water at the perimeter of the former Rolling Knoll landfill near Green Village, New Jersey, and an electromagnetic survey of the parts of the landfill within the Great Swamp National Wildlife Refuge were conducted during 1989. Results of the water-quality reconnaissance indicate that cadmium, lead, silver, and zinc were present in surface water and ground water adjacent to the Rolling Knoll landfill, although the concentrations of these constituents did not exceed New Jersey drinking-water regulations for these constituents. Concentrations of dissolved iron varied from 64 to 57,000 micrograms per liter; of the surface-water and groundwater samples collected, two-thirds exceeded New Jersey secondary drinking-water regulations. Several organic compounds were detected and were tentatively identified as pharmaceuticals or related compounds. Organic compounds were detected in surface water on the southern and western sides of the landfill, and polycyclic aromatic compounds, insecticides, and polychlorinated biphenyls were detected in samples of stream-bottom materials in Loantaka Brook. Trace elements (other than lead) generally were present in concentrations greater than background levels only in samples of surface water and ground water collected east and south of the landfill. Lead was detected in samples of surface water and ground water collected east and south of the landfill and in samples from two surface-water sample sites in the western and southwestern parts of the study area, near Loantaka Brook. Results of the electromagnetic survey were consistent with the lithologic descriptions of cores collected from hand-augered holes around the perimeter of the landfill. On the basis of the results of the waterquality analyses and the distribution of sands and clays inferred from the results of the electromagnetic survey, sites were identified at which installation of observation wells would allow for monitoring of the possible effects of the landfill on water quality in the area.
A standpipe system was developed for testing the reliability of ground water samplers. The unit consists of a stainless steel pipe 5 inches (13 centimeters) in diameter and 100 feet (30.5 meters) in height. It has 14 sampling ports from which control samples can be withdrawn at the same time and position as the samples are collected by a sampler lowered to that position. Test solutions were made in two mixing tanks, totaling 260 gallons (980 liters), by diluting the concentrate of five volatile chlorohydrocarbons in water at two levels of concentration: 10‐to‐30 and 100‐to‐200 parts per billion (micrograms per liter).
A gas chromatograph interfaced with a purge‐and‐trap system was used to perform the analyses. Comparisons of the control samples with the sampler‐collected samples have indicated that the three non‐pumping samplers had recoveries in the range of 92.4 to 103.5 percent and the three pumping samplers had recoveries ranging from 97.7 to 101.5 percent.
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