Georgia Water Resources Conference

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Georgia Water Resources Conference

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Georgia Water Resources Institute

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Now showing 1 - 10 of 11

Modeling the Effect of Slope and Precipitation on Lateral Flow in a Piedmont Soil

(Georgia Institute of Technology, 1999-03) Crisfield, Elizabeth ; Radcliffe, David E.

Nutrient contamination of surface water has received more attention in recent years prompting scientists to look for ways to protect water quality. Success in this effort will depend on a complete understanding of both surface and subsurface flow, especially in the dynamic period during and just after a storm. This study provides a theoretical estimate of lateral flow using the computer model VS2DT (Variably Saturated Two Dimensional Transport). Model storms with two-year return periods were used to estimate the percent of the total infiltration that flowed laterally under four slope conditions. The volume of lateral flow was directly related to the slope, with the 2, 5, 10, and 20-degree slopes contributing 0.8, 2.05, 5.96, and 12.00% after seven days of drainage following a 2-hour storm of 2.54 cm/hr precipitation rate. A shorter, more intense storm resulted in higher percentages of lateral flow (10. 71 % for the 10- degree slope.) Timing and total volume of lateral flow were also effected by storm distributions.
AWARE Team Activities in Georgia

(Georgia Institute of Technology, 1999-03) Risse, L. Mark ; Radcliffe, David E. ; Harris, Glen ; Newton, G. Larry ; Worley, John ; Cabrera, Miguel L.

This paper will discuss the development of the AWARE (Animal Waste Awareness in Research in Extension) team and some of its recent activities. It will cover the goals of the team and how it functions to obtain these goals. It will also discuss some of the tools the team uses including the webpage, listserve, and meetings and discuss how they are helping people throughout the state with information exchange on animal waste management issues. It will also discuss some of the AWARE teams past activities and plans for future activities.
Water Quality of Runoff and Leachate from an Improved Dairy Loafing Area

(Georgia Institute of Technology, 1999-03) McVay, K. A. ; Radcliffe, David E.

To lessen soil erosion due to high animal stocking rates on small Georgia dairies, the Natural Resources and Conservation Service (NRCS) recommends a system that utilizes geotextile material covered with crusher run gravel as a soil cover in high animal traffic areas. Soil erosion is dramatically reduced, yet due to the large accumulation of manure, questions remain concerning water quality with these systems. At a 120 cow dairy in Oglethorpe county Georgia, a loafing lot utilizing this system was constructed on a Pacolet sandy loam soil (clayey, kaolinitic, thermic, Typic Kanhapludult). Runoff water and leachate were characterized by storm events for water balance and chemical information. Surface runoff water typically contained levels of NH₄-N, and P₄-P that exceeded EPA guidelines for surface water. Sub-surface drainage intercepted by tile drains had N₃-N levels ranging from 10 to 40 ppm exceeding the EPA drinking water standard. It is recommended that surface water running off improved loafing lots either be routed to a wastewater lagoon for irrigation, or to adjacent hay fields to reduce the impact of excess nutrients to surface waters.
Role of a Stakeholder Advisory Group in Developing C.A.F.O. Regulations in Georgia

(Georgia Institute of Technology, 1999-03) Radcliffe, David E. ; Risse, L. Mark ; Thompson,Justine

In June, 1998 the State Environmental Protection Division (EPD) convened a group of approximately 90 stakeholders with an interest in regulations for concentrated animal feeding operations (CAFO's). The members represented public interest groups, producers, academia, and state and federal agencies. They were asked to consider revisions to the current requirements for National Pollution Discharge Elimination System (NPDES) permits for CAFO's and the creation of several size categories with escalating requirements. Currently permits are required for animal feeding operations with more than 1,000 animal units (AU) and a wet manure system. Four subcommittees were formed consisting of 12-14 members each: 1) size classification and regulatory system, 2) location restrictions, odors, and setbacks, 3) nutrient management and monitoring, and 4) design and administration. There was consensus to require nutrient management plans, training and certification of operators, and riparian buffers for operations larger than 300 AU. There was no consensus on whether a smaller size category starting at 100 AU should be required to register, or a large category starting at 2,000 AU should require more stringent measures. There was agreement for location restrictions for recharge areas, deep sands and wet soils, endangered species habitat, the 11 counties of Coastal Management Area, impaired streams, and wild and scenic rivers.
Differences of Soil Water Use, Lint and Biomass Yield in No-till and Conventionally Tilled Cotton in the Southern Piedmont

(Georgia Institute of Technology, 1999-03) Endale, Dinku M. ; Radcliffe, David E. ; Steiner, Jean L. ; Cabrera, Miguel L. ; McCracken, D. V. ; Vencill, B. V. ; Lhor, L. ; Schomberg, H. H.

The southeast, despite its abundant rainfall, suffers short-term summer droughts with detrimental effect on crop yield. No-till production systems provide added insurance against such conditions by improving infiltration, and conserving moisture in drought-prone soils. In three years of experiment near Watkinsville, GA, no-till cotton treatments maintained higher soil moisture content, more vegetative growth and higher lint yield than conventional tillage treatments. A combination of no-till and poultry litter treatments did even better compared to conventional tillage and conventional fertilizer treatments.
Impact of Poultry Mortality Pits on Farm Groundwater Quality

(Georgia Institute of Technology, 1999-03) Myers, Lee M. ; Bush, Parshall B. ; Segars, W. I. ; Radcliffe, David E.

Results of a 15-county survey revealed that intensive animal agriculture may impact shallow groundwater resources. Objectives of this study are to assess water quality on poultry farms and determine if there is a relationship between waste disposal practices and groundwater quality. Twenty poultry farms representing concentrated areas of commercial poultry production and four major soil provinces were evaluated using site assessments, questionnaires, electromagnetic (EM) survey readings, and chemical and microbiological analysis of domestic well water. Based upon the EM survey results, five farms were instrumented with lysimeters and test wells to determine possible nutrient and microbiological movement to groundwater. Site evaluations revealed that 10 of the 47 (21 %) domestic wells did not have appropriate well head protection to prevent surface water contamination. Five of the 47 (11 %) wells were located downslope and/or within 100 ft. of a nitrogen source other than pits and averaged nitrate-N (N03-N) levels above background (3 ppm). Thirty-eight percent had elevated coliform levels and 10.6% contained Salmonella in at least one sample during the sampling period. EM surveys and monitoring data indicated that nutrients migrate less than 100 ft. laterally down gradient from the pits. Poultry mortality pits on the 20 farms did not appear to elevate nitrate levels above background. Groundwater nitrate-N levels were higher on farms containing uncovered litter stacks. Preliminary results indicate that uncovered litter stacks may have a greater impact on groundwater quality than poultry mortality pits. Additional testing on various soil types is needed.
N and P Edge-of-field Losses from Poultry Litter Applications

(Georgia Institute of Technology, 1997-03) Vervoort, R. W. ; Radcliffe, David E. ; Cabrera, Miguel L. ; Latimore, M., Jr.

Excess application of poultry litter may cause pollution of surface and ground water with Nitrogen (N) and Phosphorus (P). Composting poultry litter could reduce the risk of pollution by creating more stable organic components. Three rates of poultry litter and compost (10 Mg he litter, 20 Mg he litter and 10 Mg he litter combined with 50 Mg ha' compost) to three watersheds under pasture. The watersheds were monitored for surface and subsurface flow. Nitrate concentrations in subsurface flow did not exceed the U.S. Environmental Protection Agency drinking water standard of 10 mg Soluble P concentrations in runoff were high, reaching a maximum of 8.5 mg L4 under the compost treatment. Concentrations of P in soil in the top 15 cm increased dramatically under the compost treatment which creates a high potential for future runoff of P. Total losses of N and P were low, mainly due to few runoff and subsurface events.
Sulfate and Phosphate Displacement of Arsenic from Fly Ash Amended Soil

(Georgia Institute of Technology, 1997-03) Qafoku, Nikolla P. ; Kukier, Urszula ; Sumner, Malcolm E. ; Miller, William P. ; Radcliffe, David E.

Arsenic (As) is the biggest environment contaminant in most of the soils where fly ash is applied. As is usually not mobile and strongly adsorbed onto soil particles. However, in gypsum and phosphorus amended soils As may be much more mobile. A study in repacked columns with soil from Ap horizon was conducted to determine whether or not As becomes mobile when Ca(H₂PO₄)₂ and CaSO₄ are used as leaching solution, and to compare the competitive interactions between PO₄-AsO₄ and SO₄.-AsO₄. As concentration in leachate was approximately ten times greater when Ca(H₂PO₄)₂ was used to leach the columns as compare to CaSO₄. A concentration of 800 µg As L⁻¹ was found in this case, which is sixteen times the limit of 50 µg As L⁻¹ established by the EPA for groundwater. In fly ash the portion of arsenate non-specifically adsorbed is believed to be much lower than that of arsenate specifically adsorbed. Sulfate anions were able to displace only non-specifically adsorbed arsenate. However, the concentration of As in leaching solution was found to be within acceptable limits. Phosphate can compete with arsenate for all available adsorption sites, non-specific and specific.
Using Ground Electromagnetic Conductivity to Determine the Source of Nitrate in Dairy Wells

(Georgia Institute of Technology, 1995-04) Radcliffe, David E. ; Brune, D. E. ; Drommerhausen, D. J.

recent study of dairies in a five-county area in north Georgia found a high incidence of nitrate nitrogen (NO3-N) contaminated well water. We used a ground electromagnetic (EM) conductivity meter to survey nine dairies in the region to determine the source of contamination. Ground EM conductivities were highest in the loafing areas on most dairies. These are the corrals or small fields near the barn where the milking herd is kept when it is not in the barn or on pasture, and other areas near the barn where there is high animal traffic. Conductivities were typically in the range 15 - 20 mS in -1 in these areas, compared to less than 10 mS ni l in the pastures away from barns. Water samples from groundwater observation wells installed in the loafing areas on three diaries had NO,-N concentrations of 47-135 mg/L compared to 12-16 mg/L from a well in a pasture. There was evidence of seepage at four of the seven wastewater lagoons we surveyed, but the loafing areas appeared to be a greater threat to drinking water supplies because they were closer to the milking barn where the supply well was located and because they affected a larger area than the lagoons. Best management practices need to be developed that address nitrate leaching from loafing areas.
Determination of Soil Contaminant Transport Parameters Using Time Domain Reflectometry

(Georgia Institute of Technology, 1993-04) Radcliffe, David E. ; Tillotson, P. M. ; Hendrix, P. F. ; West, Larry T. ; Tollner, E. W. ; Box, J. E.

A recent study of rural shallow drinking wells found that 4.6% of the wells in the Piedmont region of Georgia had nitrate levels above the EPA recommended level of 10 ppm nitrate nitrogen (Tyson and Issac, 1991). The most likely sources of this nitrate are septic systems, fertilizers, and manures. Nitrate transport models such as LEACHN (Wagenet and Hutson, 1989) can be used to investigate the contributions of these sources to groundwater contamination, but the models require soil transport parameters that are difficult to measure. Another problem is that we are interested in predicting nitrate transport at the field scale, but transport parameters are usually measured on a much smaller soil volume.