Groundwater monitoring plan for the Missouri River alluvial aquifer in the vicinity of the City of Independence, Missouri, well field

Abstract

Horizontal coordinate information is referenced to the insert datum name (and abbreviation) here, for instance, "North American Datum of 1983 (NAD 83)" Altitude, as used in this report, refers to distance above the vertical datum. Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C). Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L).

Concentration comparison of selected constituents between groundwater samples collected within the Missouri River alluvial aquifer using purge and pump and grab-sampling methods, near the city of Independence, Missouri, 2013

“…This study was designed to compare constituent concentrations between samples collected within the Independence well field using the pump method and the grab method. Monitoring wells were sampled during 2013 and included those having groundwater travel times from monitoring well to supply well ranging from 0.5 years to 10 years (Kelly, 2011;Wilkison, 2011). Grab samples were collected by deploying HydraSleeve™ grab samplers in selected wells, allowing a calculated equilibrium period of 7 days, and retrieving samplers.…”

“…Several nonpoint and point contamination sources were identified within the contributing recharge area, including, but not limited to, landfill presence, sewage sludge application areas, commercial development, highway construction, a closed oil refinery, and agricultural activity (Kelly, 1996;Kelly, 2002a). These contamination threats increase the need to monitor the quality of groundwater supplied by Independence (Kelly, 1996;Kelly, 2002a;Kelly, 2011;Wilkison, 2011). During 1997 and 1998 a network of monitoring wells (see table 1 in Kelly, 2002a for detailed monitoring well information) was established within the area of supply wells (Independence well field, fig.…”

“…1) and groundwater sampling began. The current groundwater monitoring program was designed to assess water quality and monitor temporal changes in groundwater that has a simulated travel time of less than 10 years from monitoring well to supply well (10-year zone of contribution; Wilkison, 2011). Water-quality samples were collected from specific wells at various time intervals using the pump method with a portable submersible pump according to the USGS National Field Manual for the Collection of Water-Quality Data (U.S. Geological Survey, variously dated) to target specific source areas, assess aquifer water quality, and identify potential contamination in sufficient time to take action before the contaminant reaches the supply well (Kelly, 2002a;Wilkison, 2011).…”

“…Because of this and the duplicate data results, the screened interval lengths of monitoring wells within the Independence well field are not conducive to collecting multiple grab samples by tethering samplers. Quality assurance duplicate samples are included in the groundwater monitoring plan for the Independence well field (Wilkison, 2011). The inability to collect required quality assurance samples using two tethered grab samplers may limit the use of grab samplers.…”

“…The U.S. Geological Survey, in cooperation with the City of Independence, Missouri, Water Department (hereafter referred to as Independence), has historically collected waterquality samples using the purge and pump method (hereafter referred to as pump method) to identify potential contamination in groundwater supply wells within the Independence well field (Kelly, 2002a;Wilkison, 2011). Pump methods require purging the well before sampling by removing large volumes of water (generally at least three well casing volumes) until water-quality properties stabilize (see Purge and Pump Sampling Methods).…”