Chris Crockett

harvested pipe bench scale studies showed a strong relationship between nitrate and elevated lead from lead/tin solder. Industry should consider possible unintended consequences of higher nitrate levels on lead release when changing source waters or during seasonal runoff events.

Philadelphia Water Department's source water assessment led to a carefully developed, multifaceted plan that extends into two key watersheds and ensures protection of the region's water supply.

Discusses and presents the data of the growing green roof construction in Philadelphia and how Philadelphia is a national leader in green roof innovation

Documents the concepts and technical derivation of the Philadelphia Rivercast System that predicts the real time bacteria levels in the Schuylkill River for Recreation

Discussion and critical review of the linkages between emerging pathogens from wastewater and drinking water and integration of the Clean Water Act and Safe Drinking Water Act

Authored Chapter on Watershed Management Practices

Award Winning Paper for 2004 about the state of early warning systems for water supplies in the U.S.

Byun, Seung Ah & Smullen, James & Maimone, Mark & Dickinson, Robert & Crockett, Christopher. (2003). Overcoming Obstacles in Applying SWMM to Large-Scale Watersheds. Journal of Water Management Modeling. 10.14796/JWMM.R215-02.

Discusses the impacts of land use from development and climate on water quality changes in the Schuylkill River

he Schuylkill Runoff Loading Model was developed as part of the Schuylkill River Sourcewater Assessment Program. The Storm Water Management Model (SWMM) was used to estimate quantities of contaminant loadings as a result of rainfall-runoff. Continuous SWMM is used to generate unit area loads for a 10-year simulation period and provides statistical estimates of seasonal and annual watershed loadings. The contributions from each of the sub-watersheds were found for each of the nine contaminant… Show more

he Schuylkill Runoff Loading Model was developed as part of the Schuylkill River Sourcewater Assessment Program. The Storm Water Management Model (SWMM) was used to estimate quantities of contaminant loadings as a result of rainfall-runoff. Continuous SWMM is used to generate unit area loads for a 10-year simulation period and provides statistical estimates of seasonal and annual watershed loadings. The contributions from each of the sub-watersheds were found for each of the nine contaminant categories modeled. The estimation of runoff loads for the Schuylkill Watershed using SWMM is part of a larger susceptibility analysis for the source water assessments. Identification and prioritization of significant sources of pollutants is valuable, not only to the Source Water Assessment process, but also for the overall watershed management planning efforts. Show less

The Philadelphia Water Department's Office of Watersheds Source Water Protection Program embarked upon a comprehensive Source Water Assesssment (SWA) project to identify challenges to, and priorities for, the protection of raw drinking water supplies in the region. The project is intended to identify and prioritize potential sources of contamination across the watersheds and to assess the vulnerability and susceptibility of the water supplies to these sources. An extensive watershed-wide… Show more

The Philadelphia Water Department's Office of Watersheds Source Water Protection Program embarked upon a comprehensive Source Water Assesssment (SWA) project to identify challenges to, and priorities for, the protection of raw drinking water supplies in the region. The project is intended to identify and prioritize potential sources of contamination across the watersheds and to assess the vulnerability and susceptibility of the water supplies to these sources. An extensive watershed-wide inventory of potential contaminant sources, supported by significant database and GIS efforts, was central to the development of the SWA process. The need to provide estimates of potential nonpoint source contaminant loads from subbasins over the two watersheds presented one of the more difficult challenges in the execution of the SWA project. To meet this challenge, comprehensive, watershed-wide, long-term continuous simulation models of watershed hydrology and water quality loading were applied. The runoff loading models combined with GIS, displays spatially, the areas with high pollutant loads and of high protection priority. The use of a complex deterministic model that attempts to represent rainfall-runoff, groundwater, and water quality contaminant contributions realistically at this scale is unique among the SWAs being performed across the United States today. Show less

Discussion of watershed sources of emerging pathogens

Dose–response data on human exposure to oocysts of Cryptosporidium were analyzed to determine the dose corresponding to a stated risk level.

A recent study of infection and illness in human volunteers subjected to controlled exposure to oocysts of Cryptosporidium parvum provided a suitable data base for dose–response analysis. The authors analyzed the study data, and using exponential and beta-poisson dose–response models, arrived at an estimate of the waterborne concentrations… Show more

Dose–response data on human exposure to oocysts of Cryptosporidium were analyzed to determine the dose corresponding to a stated risk level.

A recent study of infection and illness in human volunteers subjected to controlled exposure to oocysts of Cryptosporidium parvum provided a suitable data base for dose–response analysis. The authors analyzed the study data, and using exponential and beta-poisson dose–response models, arrived at an estimate of the waterborne concentrations associated with various risk levels. Show less

Every year there are estimated 300000 cases of Shigella in the United States (Bennett et al., 1987, Am. J. Prev. Med. 3, 102-114). A beta-poisson model was fit to human dose-response information on pathogenic Shigella using the Maximum Likelihood Estimation technique (Haas, 1983, Am. J. Epidemiol. 118, 573-582). Pooled and separate data sets for the Shigella species were fit to the beta-Poisson model and 95% confidence limits and regions were calculated. Shigella dysentariae and Shigella… Show more

Every year there are estimated 300000 cases of Shigella in the United States (Bennett et al., 1987, Am. J. Prev. Med. 3, 102-114). A beta-poisson model was fit to human dose-response information on pathogenic Shigella using the Maximum Likelihood Estimation technique (Haas, 1983, Am. J. Epidemiol. 118, 573-582). Pooled and separate data sets for the Shigella species were fit to the beta-Poisson model and 95% confidence limits and regions were calculated. Shigella dysentariae and Shigella flexneri confidence regions and limits overlapped with each other and with the pooled data set, suggesting that this model can describe Shigella in general. The pooled Shigella model as well as the upper and lower confidence limits of the three data sets showed average exposures based on the estimated U.S. caseload of pathogenic Shigella of 0.01 to 0.014 organisms (confidence limits 0.001-0.05) for a 7-day per annum period of exposure and ranges from 0.07 to 0.1 organisms (confidence limits 0.006-0.4). for a 1-day per annum period of exposure. The plausibility of the pooled dose-response model was then evaluated by comparison with two known cruise ship outbreaks. The pooled model estimated that the two outbreaks studied could have been due to ingestion of 344 (confidence limits 72-915) Shigella cells per meal and 10.5-12 (confidence limits 1-44) Shigella cells per glass of water by passengers. Show less

Eliminating bias while balancing sensitivity and cost are important issues for ICR monitoring of Giardia and Cryptosporidium.

The proposed Information Collection Rule may require utilities to monitor source and finished waters for Giardia and Cryptosporidium and to use the data for compliance with treatment requirements imposed by the Enhanced Surface Water Treatment Rule. Variations in sample collection and analytical methods, water quality, weather conditions, and proposed averaging… Show more

Eliminating bias while balancing sensitivity and cost are important issues for ICR monitoring of Giardia and Cryptosporidium.

The proposed Information Collection Rule may require utilities to monitor source and finished waters for Giardia and Cryptosporidium and to use the data for compliance with treatment requirements imposed by the Enhanced Surface Water Treatment Rule. Variations in sample collection and analytical methods, water quality, weather conditions, and proposed averaging methods could result in widely varying detection limits; in certain cases detection limits could easily be inaccurately pushed beyond 100 organisms/100 L. The optimal balance between sample cost and laboratory analysis is achieved by examination of 1–3 membrane filters, depending on source water turbidity. Improved monitoring results and detection limits may prevent decisions to institute unnecessary and possibly expensive treatment. Show less

Coming soon - In review