Effects of the Broome County municipal landfill's clay cap on the surface and groundwater hydrology of the Castle Creek watershed

This study analyzed for impacts of the Broome County Nanticoke Landfill on the Brook's Creek watershed's physical and chemical hydrology. Brooks Creek Watershed is the main watershed of concern, which contains the landfill at its headwaters. Potato Creek, the adjacent watershed to the north, is used in this study in comparison due to similarities in area, topography, soils, and land use. In addition, several stream and groundwater sites within the larger Castle Creek Watershed were monitored. During September 2002 -- October 2003, weekly and storm event discharge measurements, precipitation measurements, pan evaporation measurements, in situ stream pH and TDS measurements, and geochemical sampling were performed. Soil infiltration rates were measured during the fall of 2003. Geochemical sampling consisted of weekly and storm event grab samples.;Based on weekly manual measurements, Brooks Creek watershed consistently had a higher discharge rate than the Potato Creek watershed. These results may be attributed to its larger area and relief. Due to field problems with automated stream stage loggers, these data could not be used for more detailed analyses. Brooks Creek also had higher annual stream bank erosion rates (11.5 tons/yr/km) than Potato Creek (5.4 tons/yr/km) based on field assessment and analyses by AVStrEAMS software. Using a Guelph permeameter, the Volusia soil association's saturated hydraulic conductivity was calculated at locations throughout Potato and Brooks Creek watersheds. The mean value for the locations sampled (1.9 cm/hr +/- 1.6 cm/hr) falls into the range for fine (10 -2 -- 100 cm/hr) to well-sorted (100 -- 102 cm/hr) sands.;TR-20 was used to model storm water runoff for the Brooks Creek watershed. Different input parameters were used to examine runoff with the existing landfill and also if there were no landfill. The 1-year, 2-year, 5-year, 10-year, 25-year, 50-year, and 100-year events were modeled. The results show that there is not a significant difference in storm water runoff between the two scenarios (< 4% in peak outflow). This indicates that the landfill, which is 5% of the area of the Brooks Creek watershed, has a small effect on the physical hydrology of the watershed.;The water quality data collected in this study may indicate a substantial chemical effect of the landfill in the Brooks Creek watershed and also partial remediation of the leachate by a natural wetland near the watershed headwaters. In general, the geochemical data shows stream waters as would be expected from the chemical weathering of the materials comprising the soils in this area. However, a number of the water quality parameters measured, conductivity, Cl-, NO3-, and SO4 -, are chemical indicators for landfill leachate. All were present at elevated levels in samples collected at two sites on a small tributary to Brooks Creek down gradient of where the treated landfill leachate is discharged. The concentrations of these parameters decreased by 32% - 65% from these sites to the monitoring station on upper Brooks Creek, as did all measured metals (25% - 67%). These decreases could be explained by the natural wetland located between the sites removing some of the anions and cations from the landfill's output. Despite these reductions, the levels of three of the landfill indicator chemicals, Conductivity, Cl-, and SO4-, in Upper Brooks Creek exceed those in Upper Potato Creek by 34%, 44%, and 67%, respectively. Similarly, the concentrations of Conductivity, Cl-, and SO4- in Lower Brooks Creek are 28%, 37%, and 68% higher, respectively, than those in Lower Potato Creek. In addition, NO 3- concentrations are 34% higher in Lower Brooks Creek than those in Lower Potato Creek. Mean concentrations of all metals except iron were also higher in Brooks Creek than in Potato Creek by 9% - 61%. This comparison between the two watersheds may indicate the impact of the landfill leachate on the stream water chemistry through the Brooks Creek watershed. (Abstract shortened by UMI.)...