POTENTIAL IMPACT OF EARTHEN WASTE STORAGE STRUCTURES ON WATER RESOURCES IN IOWA¹

Abstract

Earthen waste storage structures (EWSS) associated with large confined (concentrated) animal feeding operations (CAFOs) were evaluated for their potential to impact water resources in Iowa. A representative sample of 34 EWSS from a digital database of 439 lagoons and basins permitted between 1987 and 1994 was analyzed. Eighteen percent (6 of 34) directly overlie alluvial aquifers that are used widely for potable water supply. Ninety‐four percent (29 of 31) were constructed below the water table based on EWSS depth data. At 65 percent of EWSS (22 of 34), 50 percent or more of the manure‐spreading area (MSA) has a water‐table depth less than 1.6 m. At 74 percent of EWSS (25 of 34), 90 percent or more of the MSA contains soil with vertical K exceeding 25.4 mm/hr. Seventy‐one percent (24 of 34) occur where 10 percent or less of the MSA is frequently flooded. No significant differences were found among leakage rates due to aquifer vulnerability class or surficial material. However, at least 50 percent of EWSS (14 of 28) leaked at rates significantly greater than 1.6 mm/d under the new construction standard. The estimated 5,000 unregulated CAFOs may have a greater potential to impact water resources in Iowa.

Fracture‐Controlled Nitrate and Atrazine Transport in Four Iowa Till Units

“…T ill units of Pre‐Illinoian to late Wisconsinan age have generally been viewed as impermeable materials that preclude vertical and horizontal transport of surficial contaminants to aquifers and surface waters in Iowa. This idea has been extended to point sources such as landfills and hazardous waste sites and nonpoint sources including surface‐applied nutrients and herbicides, and seepage of effluent from sewage and swine manure lagoons (Simpkins et al, 2002). Studies have suggested, however, that significant nitrate and herbicide contamination of the underlying aquifers has occurred in many areas.…”

“…This idea has been extended to point sources less than the total porosity ( T ) of till (McKay et al, such as landfills and hazardous waste sites and nonpoint 1993a; Jørgensen et al, 1998). Advective velocity of sources including surface-applied nutrients and herbisolutes in fractured systems may be estimated by the cides, and seepage of effluent from sewage and swine average linear velocity equation: manure lagoons (Simpkins et al, 2002). Studies have…”

Addressing Externalities From Swine Production to Reduce Public Health and Environmental Impacts

“…Moreover, one Iowa study found that more than half of the manure storage structures tested leaked at rates above the legal limit. 12 There are approximately 5600 such structures in the state. The Environmental Integrity Project report documented 329 manure spills in Iowa between 1992 and 2002.…”

Nonpoint Sources

“…Animal waste management is an important component of controlling nonpoint source pollution. Simpkins et al (2002b) looked at the potential impact of earthen waste storage structure (EWSS) on water resources in Iowa. They found that a large number of EWSS associated with large confined (concentrated) animal feeding operations (CAFOs) have a greater potential to impact water resources.…”