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ProUCL Version 4.0 Technical Guide
Citation:
SCHUMACHER, B. A., A. SINGH, A. SINGH, AND J. M. NOCERINO. ProUCL Version 4.0 Technical Guide. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-07/041 (NTIS PB2007-107919), 2007.
Impact/Purpose:
The overall objectives of this task are to: 1) provide ORD state-of-the-science technical support and assistance to Regional staff; 2) facilitate the evaluation and application of site characterization technologies at Superfund and RCRA sites; and 3) improve communication among Regions and ORD laboratories.
Description:
Statistical inference, including both estimation and hypotheses testing approaches, is routinely used to: estimate environmental parameters of interest, such as exposure point concentration (EPC) terms, not-to-exceed values, and background level threshold values (BTVs) for contaminants of potential concern (COPCs); identify areas of concern (AOCs) at a contaminated site; compare contaminant concentrations found at two or more AOCs of a contaminated site; compare contaminant concentrations found at an AOC with background or reference area contaminant concentrations, and; compare site concentrations with a cleanup standard to verify the attainment of cleanup standards. Several exposure and risk management and cleanup decisions in support of United States Environmental Protection Agency (EPA) projects are made based upon the mean concentrations of the COPCs. A 95% upper confidence limit (UCL95) of the unknown population (e.g., an AOC) arithmetic mean (AM), µ1, can be used to: estimate the EPC term of the AOC under investigation; determine the attainment of cleanup standards; compare site mean concentrations with reference area mean concentrations, and estimate background level mean contaminant concentrations. The background mean contaminant concentration level may be used to compare the mean of an area of concern. It should be noted that it is not appropriate to compare individual point-by-point site observations with the background mean concentration level. ProUCL Version 4.0 (ProUCL 4.0) is an upgrade of ProUCL Version 3.0 (EPA, 2004). ProUCL 4.0 contains statistical methods to address various environmental issues for both full data sets without nondetects (NDs) and for data sets with NDs (also known as left-censored data sets). ProUCL 4.0 retains all of the capabilities of ProUCL 3.0, including Goodness-of-Fit tests for a normal, lognormal, and a gamma distribution and computation of UCLs based upon full data sets without nondetects. ProUCL 4.0 has improved graphical methods, which may be used to compare the concentrations of two or more populations such as: site versus background populations; surface versus subsurface concentrations; concentrations of two or more AOCs, and identification of mixture samples and/or potential outliers. ProUCL 4.0 serves as a companion software package for the UCL Computation Guidance Document for Hazardous Waste Sites (EPA, 2002a) and the Background Guidance Document for CERCLA Sites (EPA, 2002b). ProUCL 4.0 is also useful to verify the attainment of cleanup standards (EPA, 1989). ProUCL 4.0 can also be used to perform two sample hypotheses tests and to compute various upper limits often needed in groundwater monitoring applications (EPA, 1992 and EPA, 2004).