The Passaic Formation consists of gradational sequences of mudstone, siltstone, and sandstone, and is a principal aquifer in central New Jersey. Ground-water flow is primarily controlled by fractures interspersed throughout these sedimentary rocks and characterizing these fractures in terms of type, orientation, spatial distribution, frequency, and transmissivity is fundamental towards understanding local fluid-transport processes. To obtain this information, a comprehensive suite of geophysical logs was collected in 10 wells roughly 46 m in depth and located within a .05 km 2 area in Hopewell Township, New Jersey. A seemingly complex, heterogeneous network of fractures identified with an acoustic televiewer was statistically reduced to two principal subsets corresponding to two distinct fracture types: (1) bedding-plane partings and (2) high-angle fractures. Bedding-plane partings are the most numerous and have an average strike of N84° Wand dip of 20° N. The high-angle fractures are oriented subparallel to these features, with an average strike of N79° E and dip of 71 0 S, making the two fracture types roughly orthogonal. Their intersections form linear features that also retain this approximately east-west strike. Inspection of fluid temperature and conductance logs in conjunction with flowmeter measurements obtained during pumping allows the transmissive fractures to be distinguished from the general fracture population. These results show that, within the resolution capabilities ofthe logging tools, approximately 51 (or 18 percent) of the 280 total fractures are water producing. The bedding-plane partings exhibit transmissivities that average roughly 5 m 2 /day and that generally diminish in magnitude and frequency with depth. The high-angle fractures have average transmissivities that are about half those of the bedding-plane partings and show no apparent dependence upon depth. The geophysical logging results allow us to infer a distinct hydrogeologic structure within this aquifer that is defined by fracture type and orientation. Fluid flow near the surface is controlled primarily by the highly transmissive, subhorizontal bedding-plane partings. As depth increases, the high-angle fractures apparently become more dominant hydrologically.
Element, provided information on technical details and reviews, including terminology used by soil scientists and groundwater hydrologists. Joseph Skupien, Storm Water Management Consulting, provided extremely valuable insights into basin-design criteria and other subtleties of how developers in New Jersey meet stormwater management regulations. The members of the American Water Resources Association (AWRA) New Jersey Section Stormwater-Best-Management-Practices-Mounding Technical Guidelines Workgroup participated in technical discussions that identified the need for quantitative assessment of variables affecting groundwater mounding. Nicholas Trainor (Rutgers University, Department of Applied Mathematics) used sophisticated mathematical software to solve the Hantush equation and Hunt equation to verify that Excel spreadsheets used in this report accurately solved the analytical equations.
Graphs showing-26. Simulated monthly base flow during predevelopment, post-development, and maximum allocation conditions at streamflow-gaging stations (a) Scotland Run near Williamstown, N.J. (01411460); (b) Scotland Run at Fries Mill, N.J.
Volatile organic compounds, predominantly trichloroethylene and its degradation products, have been detected in ground water at the Naval Air Warfare Center (NAWC), West Trenton, New Jersey. An air-stripping pump-and-treat system has been in operation at the NAWC since 1998. An existing groundwater flow model was used to evaluate the effect of a change in the configuration of the network of recovery wells in the pump-and-treat system on flow paths of contaminated ground water. The NAWC is underlain by a fractured-rock aquifer composed of dipping layers of sedimentary rocks of the Lockatong and Stockton Formations. Hydraulic and solute-transport properties of the part of the aquifer composed of the Lockatong Formation were measured using aquifer tests and tracer tests. The heterogeneity of the rocks causes a wide range of values of each parameter measured. Transmissivity ranges from 95 to 1,300 feet squared per day; the storage coefficient ranges from 9 x 10-5 to 5 x 10-3 ; and the effective porosity ranges from 0.0003 to 0.002. The average linear velocity of contaminated ground water was determined for ambient conditions (when no wells at the site are pumped) using an existing groundwater flow model, particle-tracking techniques, and the porosity values determined in this study. The average linear velocity of flow paths beginning at each contaminated well and ending at the streams where the flow paths terminate ranges from 0.08 to 130 feet per day. As a result of a change in the pump-and-treat system (adding a 165-foot-deep well pumped at 5 gallons per minute and reducing the pumping rate at a nearby 41-foot-deep well by the same amount), water in the vicinity of three 100-to 165-footdeep wells flows to the deep well rather than the shallower well.
CarolThompson, and members of the facilities and grounds department was critical to the success of the field-data collection effort. Kenneth Miller (Rutgers University) and Scott Stanford (New Jersey Geological and Water Survey) provided important insights and draft interpretations of their ongoing geologic studies of the area.
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