Baker R.J.,U.S. Geological Survey |
Reilly T.J.,U.S. Geological Survey |
Lopez A.,Bayer Risse Engineering Inc. |
Romanok K.,U.S. Geological Survey |
Wengrowski E.W.,New Jersey Pinelands Commission
Waste Management | Year: 2015
A screening tool for quantifying levels of concern for contaminants detected in monitoring wells on or near landfills to down-gradient receptors (streams, wetlands and residential lots) was developed and evaluated. The tool uses Quick Domenico Multi-scenario (QDM), a spreadsheet implementation of Domenico-based solute transport, to estimate concentrations of contaminants reaching receptors under steady-state conditions from a constant-strength source. Unlike most other available Domenico-based model applications, QDM calculates the time for down-gradient contaminant concentrations to approach steady state and appropriate dispersivity values, and allows for up to fifty simulations on a single spreadsheet. Sensitivity of QDM solutions to critical model parameters was quantified. The screening tool uses QDM results to categorize landfills as having high, moderate and low levels of concern, based on contaminant concentrations reaching receptors relative to regulatory concentrations.The application of this tool was demonstrated by assessing levels of concern (as defined by the New Jersey Pinelands Commission) for thirty closed, uncapped landfills in the New Jersey Pinelands National Reserve, using historic water-quality data from monitoring wells on and near landfills and hydraulic parameters from regional flow models. Twelve of these landfills are categorized as having high levels of concern, indicating a need for further assessment. This tool is not a replacement for conventional numerically-based transport model or other available Domenico-based applications, but is suitable for quickly assessing the level of concern posed by a landfill or other contaminant point source before expensive and lengthy monitoring or remediation measures are taken. In addition to quantifying the level of concern using historic groundwater-monitoring data, the tool allows for archiving model scenarios and adding refinements as new data become available. © 2015.
Laidig K.J.,New Jersey Pinelands Commission
Ecohydrology | Year: 2012
Groundwater withdrawals in a shallow unconfined aquifer can reduce water levels in connected wetlands and lead to changes in vegetation. I simulated the effect of withdrawals on the vegetation of intermittent ponds in the New Jersey Pinelands by first characterising the vegetation communities and associated hydrologic regimes of 15 ponds. A model, which was based on these results, was used in conjunction with simulated water-level drawdowns to predict changes in plant communities. Five dominant vegetation communities found at the study ponds included Carex striata, Chamaedaphne calyculata, and Vaccinium corymbosum patch types and aquatic-herbaceous and wetland-herbaceous types, which represent combinations of other vegetation types. A vegetation-hydrology model related mean vegetation cover for the five patch types to water level in 5-cm classes. Groundwater withdrawals were simulated by reducing pond-water depth by 5-cm intervals, and the resulting changes in modelled vegetation were assessed. Aquatic-herbaceous and wetland-herbaceous patch types displayed reductions in area beginning at the smallest simulated drawdowns evaluated. C. striata patch area changed only slightly for drawdowns ≤10cm, but decreased steadily in response to greater drawdowns. C. calyculata and V. corymbosum patch areas increased for water-level reductions ≤15cm and then decreased at drawdowns ≥20cm. The area of combined pond-vegetation types, which represents the entire pond as a single vegetation community, consistently decreased at reductions of ≥10cm. These simulations suggest that groundwater withdrawals favour the expansion of woody species into intermittent ponds, with eventual replacement of pond vegetation by adjacent forest vegetation if extreme hydrologic modifications occur. © 2011 John Wiley & Sons, Ltd.
Bunnell J.F.,New Jersey Pinelands Commission |
Ciraolo J.L.,New Jersey Pinelands Commission
Wetlands Ecology and Management | Year: 2010
Wetland hydroperiod is a key factor for the reproductive success of pond-breeding amphibians. Ground-water withdrawals may cause intermittent ponds to dry prematurely, potentially affecting amphibian development. In three intermittent ponds, we monitored hydrology and tracked oviposition, larval development, and metamorphosis for three frog species that represented a range of breeding phenologies. The three species were the southern leopard frog (Lithobates sphenocephalus), spring peeper (Pseudacris crucifer), and Pine Barrens treefrog (Hyla andersonii). We simulated ground-water withdrawals by subtracting from 5 to 50 cm (in 5-cm increments) from the measured water-depth values at the ponds over a short-term (2-year) period and a long-term (10-year) period to estimate the potential impact of hydroperiod alterations on frog development. Short-term simulations indicated that 5 and 10 cm water-depth reductions would have resulted in little or no impact to hydroperiod or larval development and metamorphosis of any of the species. Noticeable impacts were estimated to occur for reductions ≥15 cm. Long-term simulations showed that impacts to the appearance of the first pre-metamorphs and metamorphs would have occurred at reductions ≥10 cm and impacts to initial egg deposition would have occurred at reductions ≥20 cm. For all simulations, successively greater reductions would have caused increasing impacts that varied by species and pond, with the 50-cm reductions shortening hydroperiods enough to practically eliminate the possibility of larval development and metamorphosis for all three species. Compared to the spring peeper and southern leopard frog, the estimated impacts of the simulations on the various life stages were the greatest for the Pine Barrens treefrog. © 2010 Springer Science+Business Media B.V.