Arsenic concentrations (ppb) in a single well at a solid waste landfill. Four observations per year over four years. Years 1-3 are the background period and Year 4 is the compliance period.
A data frame with 16 observations on the following 3 variables.
a factor indicating the year of collection
a factor indicating the sampling period (background vs. compliance)
a numeric vector of arsenic concentrations (ppb)
USEPA. (2009). Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Unified Guidance. EPA 530/R-09-007, March 2009. Office of Resource Conservation and Recovery Program Implementation and Information Division. U.S. Environmental Protection Agency, Washington, D.C. p.18-10.
USEPA. (2010). Errata Sheet - March 2009 Unified Guidance. EPA 530/R-09-007a, August 9, 2010. Office of Resource Conservation and Recovery, Program Information and Implementation Division. U.S. Environmental Protection Agency, Washington, D.C.