Browsing by Author "Heger, Sara"
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Item Evaluation of Four Milk House Wastewater Treatment Systems in Minnesota(2015-08) Heger, SaraThis project evaluated and demonstrated effective techniques and/or systems to reduce environmental pollution contained in dairy milk house wastewater and disseminated the results to dairy producers in Minnesota. With federal Clean Water Act Section 319 funding, four new or modified milk house wastewater treatment systems were demonstrated and evaluated on sixteen farms in four counties in Minnesota. All of the treatment systems had a septic tank for primary treatment. The four types of systems installed included aeration, both aerobic treatment units and recirculating media filters with discharge to subsurface soil treatment systems, irrigation to cropland or pasture, and large soil surface infiltration areas covered with bark (bark beds). The systems were monitored for influent and effluent wastewater characteristics, water flow and overall system performance. Overall the systems removed 98-100% of BOD5 and TSS, 90 to 100% of the phosphorous and 75 - 90% of the nitrogen. Lessons learned from the installation and monitoring of these systems have led to design guidelines for the selection, design, and installation of these milk house wastewater treatment systems. In addition a milk house wastewater treatment estimator was developed to document the removal of contaminants after installation of a milk house wastewater treatment system. The estimator was tested on the impaired Carver Creek watershed in Carver County, Minnesota where seven farms have direct discharge of milk house wastewater to tile lines. The estimator showed the overall impact of installing milk house treatment systems on these seven farms will be an annual removal of 10,778 pounds of BOD5, 4003 pounds of TSS, 252 pounds of phosphorous and 336 pounds of nitrogen. Economically the removal of phosphorous per pound is much lower than many other potential practices, whereas nitrogen costs are more median; indicating watersheds facing nutrient impairment with small to mid-size dairies should focus improvements in this direction.Item Investigating Wastewater Reuse at MnDOT Truck Stations(Minnesota Department of Transportation., 2019-05) Heger, Sara; Doro, Jessica; Rutter, Melissa C; Gustafson, Dave; Larson, SondraThe University of Minnesota (UMN) and the Minnesota Department of Transportation (MnDOT) conducted a study to determine whether implementing a wastewater reuse program would be a feasible option for MnDOT-owned truck washing stations. MnDOT has 137 truck stations in the state, where trucks are frequently washed to remove road salt build-up. MnDOT recognized an opportunity to potentially reuse the wastewater for appropriate greywater uses and recapture the salt for road use. Sampling was done to assess the wastewater contaminants in truck wash water at 11 truck-washing stations in Minnesota. Then technologies suited to removing organics and total suspended solids (TSS) but not chlorides were reviewed. The recommendation is that either a recirculating sand filter (RSF) or a membrane bioreactor (MBR) would be feasible technologies to use for this purpose. Using the MnDOT truck station in Arden Hills, Minnesota, an economic evaluation was done. Both systems could be used to effectively treat wastewater and produce brine for reuse, but the most economical solution for MnDOT would be to invest in a MBR. Compared with a RSF, an MBR is one-third less expensive over time, primarily due to low material and installation cost as well as a lower annual maintenance costs.Item Septic System Evaluation at MnDOT Rest Stops, Truck Stations and Weigh Scales(Center for Transportation Studies, University of Minnesota, 2016-01) Heger, Sara; Wheeler, Dan; Gustafson, Dave; Szmorlo, MikeThe University of Minnesota (UM) and the Minnesota Department of Transportation (MnDOT) performed a unique evaluation of the 52 existing subsurface sewage treatment systems at safety rest areas (SRA) travel information centers, truck stations and weigh scales at MnDOT facilities across Minnesota. This three year partnership brought together the septic expertise of the UM with the MnDOT wastewater unit’s agency and site knowledge. The goal of the assessments was to evaluate risk and provide a risk analysis ranking system. The project began with an extensive record search where many documents were digitized and a database of information created. The next step was development of a draft assessment protocol. This draft protocol was pilot tested on five systems and refined based on those experiences. The full assessment included a preliminary review of the site, a facility assessment, effluent sampling, septic tank inspections, evaluation of advanced treatment units when present and an assessment of the soil treatment system. The information from the assessment was used to develop a risk ranking of all systems. The risk assessment created can be used for planning purposes to prioritize capital upgrades, but only if a sustainable process is created and incorporated into the day to day workload.Item Water Use at Minnesota Rest Areas: Final Report(Center for Transportation Studies, University of Minnesota, 2016-01) Nelson, Taylor; Heger, SaraThe Minnesota Department of Transportation (MnDOT) Statewide Rest Area Program consists of a coordinated system of public rest areas that are intended to help motorists travel safer. In 1979, MnDOT collected data at rest areas to refine assumptions and improve techniques for design of rest area water supply and sewage treatment. They found people used an average of 2.8 gallons with water conserving devices and 4.5 gallons with non-water-conserving devices. This study evaluated the accuracy of the 1979 MnDOT design charts and formulas based on plumbing code fixtures and traffic patterns. A total of six rest areas, Culkin Rest Area (R.A.), Frazee R.A., Fuller Lake R.A., Lake Pepin R.A., Central Minnesota Travel Information Center (TIC), and St. Croix TIC, were included in the study. Average water use estimations were calculated from hourly people counts, hourly traffic counts, and hourly water flow data. Site specific average water use per person ranged from 0.7 gallons to 3.8 gallons, with an overall average water use of 2.3 gallons and a 95% confidence level average of 3.5 gallons. When accounting for variation, error and providing a safety factor, a water use per person design value of 5 gallons per person per day is recommended. The results of this two-week study appear to indicate that the 1979 design values are still valid, but additional data is needed for further conclusions. The University of Minnesota recommended MnDOT conduct similar water use studies for longer time periods prior to designing new rest area septic systems.Item Water Use at Minnesota Rest Areas: Task Report(Center for Transportation Studies, University of Minnesota, 2017-01) Nelson, Taylor; Heger, SaraThe Minnesota Department of Transportation (MnDOT) State Wide Rest Area Program is composed of a coordinated system of public rest areas and waysides, intended to help motorists travel safer. In 1979, MnDOT collected data at rest areas to refine assumptions and improve techniques for design of rest area water supply and sewage treatment designs. They found on average that with water conserving devices people used 2.8 gallons, while non-water-conserving devices used 4.5 gallons. This study evaluated the accuracy of MnDOT design charts and formulas based on people counts and water flows. A total of twelve rest areas were included in the study. Data was collected from Spring 2015 to Fall 2016. Site specific average water use per person ranged from 0.9 gallons to 4.6 gallons. A difference was found between the two building types, interstate and non-interstate, with interstate visitors averaging 2.2 ± 0.5 gallons and non-interstate visitors averaging 1.8 ± 0.7 gallons. The difference between building types was not easily explainable, however it is theorized fewer visitors at non-interstate sites results in less water needed for cleaning or water treatment. The results of this study indicate that the original design values are still valid. However, due to the wide variation of water use per site, maximum water demands and usage trends should be estimated when designing a new septic system to ensure the most appropriate septic system is installed, resulting in the successful treatment of waste water and the fulfillment of expected system lifespans without additional maintenance costs.