John R. Buchanan

Thermodynamics of Struvite Formation

Struvite is a phosphate mineral that can form hard-scale deposits in the recycle components of livestock waste management systems that utilize recycled lagoon effluent to transport waste. Previous research of struvite formation in piping systems has been hindered by the presence of erroneous solubility constant values in the literature and the use of a set of less-than-comprehensive equilibrium equations. This article identifies the erroneous solubility product constant commonly found in text books and documents an apparently correct value.

Struvite Control by Chemical Treatment

Struvite is a phosphate mineral which can form hard-scale deposits in the recycle components of livestock waste management systems that utilize recycled lagoon effluent to transport waste. Previous research of struvite formation has been directed toward acid-cleaning the recycling system after struvite has been deposited. Such systems incorporate a separate acid injection network that circulates acid through the components and dissolves the scale. The major limitations to this approach are that the operation of the waste management system must be suspended while cleansing takes place and that acids are hazardous to handle and difficult to administer.

DESIGN AND EVALUATION OF AN IMPROVED FLOW DIVIDER FOR SAMPLING RUNOFF PLOTS

An improved flow divider was designed to simplify and lower the cost of collecting runoff data from research plots. The system was designed around commercially available and inexpensive 5-gal (19-L) plastic buckets with screw top lids. A precision cut sheet-metal divider “crown” is fastened to the lid, allowing it to be easily transferred between buckets. The divider crown can be configured to handle various flow rates by specifying the number of flow divisions. Laboratory evaluation of the design indicated that the system divides runoff with accuracies within .5% over most of the flow range and within .15% at very low and very high flows. These results are similar to those found for the more traditional flow divider designs. Adding sediment to the inflow at three different flow rates yielded sediment division accuracies within 7%. Five field research projects have used the divider system with few problems. The average cost of this system is approximately US

WOOD CHIPS AS A SOIL COVER FOR CONSTRUCTION SITES WITH STEEP SLOPES

500 per plot, in comparison to the US

CONSERVATION PLANNING FOR CONSTRUCTION SITES

3000 to

THE TENNESSEE FLUID LEVEL INDICATOR

5000 it often costs to instrument a plot using standard equipment.

Fate and Transport of 17β-Estradiol beneath Animal Waste Holding Ponds.

Wood chips were studied for their efficacy in controlling soil erosion on a steep construction site with disturbed soils. The purpose of the research was twofold: to determine if wood chips could be used to reduce the off–site movement of soil during construction activities, and to find an environmentally sound alternative to the landfill disposal of wood wastes generated in the urban forest. The research was conducted on field plots that received natural precipitation. Twelve erodible plots were established on an embankment with a 55% slope and an elevation change of nearly 12 m. Each plot had a width of 3 m and a horizontal slope length of 10 m. A series of flow dividers was installed at the toe of each plot to measure runoff and sediment. Four treatments were studied: large wood chips, small wood chips, a mixture of wood chip sizes, and a control with no chips. The mixture of wood chip sizes represented the size distribution that was found to occur from chippers. The wood chips were applied at a rate that covered 80% of the soil surface. The erosion rate for the small wood chip treatment was not significantly different from the zero–cover plots. The erosion rates from the large wood chip and mixture of chip sizes were not significantly different from one another, but were significantly different from the zero–cover treatment. Overall, in comparison to the zero–cover treatment, the small wood chip treatment reduced erosion by 22%, the large wood chips reduced erosion by 78%, and the mixture of chip sizes reduced erosion by 86%. The results of this project indicate that wood chips (as produced by a chipper) should be utilized as a soil cover and need not be discarded as solid waste.

Site Selection for Subsurface Drip Irrigation Systems in the Humid Region

Although conservation planning for agricultural lands has evolved to its current relatively stable form over many decades, conservation planning for construction sites is still in its infancy. This project drew on the resources of various agencies and researchers to develop a conservation planning tool specifically geared towards meeting construction site planning needs in Wisconsin, basing it on the Revised Universal Soil Loss Equation, version 2 (RUSLE2). The project began by deconstructing the planning process itself to determine possible approaches and critical elements, and used those pieces to build a rational new approach to construction site conservation planning. Although no changes were required to the erosion or sediment delivery calculations in RUSLE2, this new tool required substantial changes to the database, the interface, and how the results were presented and packaged. The lessons learned in this effort should be instructive to both a general discussion of the construction site planning process and to attempts to develop other tools that meet this need.

DEVELOPMENT AND EVALUATION OF A DEVICE TO CONTROL TIME VARYING FLOWS

An effort to produce a low-cost yet accurate fluid level sensor led to the development of the Tennessee Fluid Level Indicator (TFLI) by researchers at The University of Tennessee Agricultural Experiment Station. This device measures fluid levels using a simple weighted tube hanging from a load cell, and can be designed to measure almost any operational range of fluid levels. The TFLI was tested in the laboratory for repeatability, degree of hysteresis, sensitivity to temperature changes, and stability of the calibration relationship with use. In every case the device performed very well, indicating that it will yield fluid level measurements within ±1 mm (0.04 in.) under normal use. Researchers have used the TFLI in the field for more than three years, and have had very little trouble with either drift or reliability. Perhaps most importantly, the TFLI can be constructed and calibrated for less than half the cost of most water-level sensors.

Performance of On-site Domestic Wastewater Renovation Systems Specified for Sites with Shallow Soils

Concentrated animal feeding operations typically store livestock waste in clay-lined ponds. Although these ponds are regulated to include a liner with a small hydraulic conductivity to limit leaching, previous studies have traced surface and groundwater contamination from such regulated animal waste ponds. This research examined the transport of 17β-estradiol (E2) and its primary metabolite, estrone (E1), through soil liners using field- and laboratory-based studies. Additionally, a potential engineering solution to limit hormone transport-applying biochar to new pond liners to act as a retardant-was studied. Soil cores 80 cm in length were collected beneath a mature dairy waste pond and analyzed for moisture content and hormone concentrations. Unsaturated conditions and E2 concentrations of 4 to 250 ng g were detected beneath the waste pond. In the laboratory portion of the study, hand-packed columns of sand or clay were subjected to infiltration by a 2.3-m head of dairy waste. A subset of the hand-packed sand columns was amended with powdered biochar to test its ability to retard E2 and E1. For 3 mo, column leachate was analyzed for hormone concentrations, and at the conclusion of the study E2 and E1 concentrations in the soil were measured. In the 44 d after sealing, the clay, sand, sand with a thin layer of biochar, and sand mixed with a biochar amendment leached a total of 0.54, 1.3, 0.09, and 0.45 μg of E2, respectively. The biochar amendments to the hand-packed columns considerably minimized E2 in the leachate.