Browsing by Subject "infiltration"

Now showing 1 - 4 of 4
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    Assessing and Improving Pollution Prevention by Swales
    (Center for Transportation Studies, University of Minnesota, 2014-08) Ahmed, Farzana; Natarajan, Poornima; Gulliver, John S.; Weiss, Peter T.; Nieber, John L.
    Roadside swales are drainage ditches that also treat runoff to improve water quality, including infiltration of water to reduce pollutant load. In the infiltration study, a quick and simple device, the Modified Philip Dunne (MPD) infiltrometer, was utilized to measure an important infiltration parameter (saturated hydraulic conductivity, Ksat) at multiple locations in a number of swales. The study showed that the spatial variability in the swale infiltration rate was substantial, requiring 20 or more measurements along the highway to get a good estimate of the mean swale infiltration rate. This study also developed a ditch check filtration system that can be installed in swales to provide significant treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff. The results were utilized to develop design guidelines and recommendations, including sizing and treatment criteria for optimal performance of the full-scale design of these filters. Finally, the best available knowledge on swale maintenance was combined with information obtained from new surveys conducted to develop recommendations for swale maintenance schedules and effort. The recommendations aim toward optimizing the cost-effectiveness of roadside swales and thus provide useful information to managers and practitioners of roadways. The research results and information obtained from this study can thus be used to design swale systems for use along linear roadway projects that will receive pollution prevention credits for infiltration. This will enable the utilization of drainage ditches to their full pollution prevention potential, before building other more expensive stormwater treatment practices throughout Minnesota and the United States.
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    Enhancement and Application of the Minnesota Dry Swale Calculator
    (Center for Transportation Studies, University of Minnesota, 2016-04) Garcia-Serrana, Maria; Gulliver, John S.; Nieber, John L.
    Roadside drainage ditches (roadside grassed swales) typically receive runoff directly from the road and water is infiltrated over the side slope of the ditch, similar to a filter strip. Water that runs off the side slopes then has a further opportunity to infiltrate as it flows down the center of the ditch. This research focuses on the volume reduction performance of grassed drainage ditches or swales by infiltration. A total of 32 tests were performed during three seasons in four different highways maintained by MnDOT in the Twin Cities metro area. The field-measured saturated hydraulic conductivities (Ksat) correspond to hydrologic soil group A, even though the soil textures indicated correspondence to hydrologic soils groups A, B and C. This means that the infiltration performance is better than expected for these types of soils. In addition, the trend was to have more infiltration when the saturated hydraulic conductivity was higher and for a greater side slope length, as expected. A coupled overland flow-infiltration model that accounts for shallow concentrated flow has been developed. The predicted infiltration loss has been compared with the actual infiltration loss determined from the monitored field tests. In this manner, the validity of the model as well as the associated soil hydraulic and surface geometry parameters have been evaluated. Using the coupled infiltration-overland flow model, multiple scenarios with sensitivity analyses have been computed, and the results have been used to generate a simplified calculator to estimate the annual infiltration performance of a grassed roadside drainage ditch.
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    Modeling Direct Recharge of Surficial Aquifers
    (Water Resources Research Center, University of Minnesota, 1983-04) Knoch, Brian C.; Larson, Curtis L.; Slack, Donald C.
    A one-dimensional, physically-based computer model was developed for predicting direct groundwater recharge. The model was verified using three years of data from an instrumented site in east central Minnesota. Although the processes of infiltration and redistribution during frozen soil periods were not modeled, the model is capable of operating during both frozen and non-frozen soil periods. The model includes submodels for evapotranspiration, soil water extraction, snowmelt, surface depressional storage, infiltration and redistribution. The model predicts water table level and soil moisture. Water extraction may also be modeled. The model predicted both water table levels and soil moisture with reasonable accuracy over the the three year period modeled.
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    Performance of Low Impact Development Practices on Stormwater Pollutant Load Abatement
    (St. Anthony Falls Laboratory, 2011-08) Ahmed, Farzana; Gulliver, John S.; Nieber, John L.
    Stormwater runoff is a major contributor to the impairment of surface waters in the United States. With high connected impervious surfaces and concentrated human activities, urban land uses are involved in discharging most of the stormwater volume and pollutant loadings during a storm. Stormwater pollution prevention involves the installation and maintenance of stormwater low impact development (LID) practices in urban areas. These include infiltration basins and trenches, porous pavements, rain gardens, vegetative swales, and filter strips. LID practices infiltrate and detain stormwater to reduce stormwater runoff volume and improve water quality via filtration and other processes. The reasons for assessing the performance of the LID practices include fulfilling stormwater permit regulatory requirements, engineering and design due diligence, scheduling maintenance and TMDL studies. The results of the assessment allow for an improved understanding of the role of the various system components (i.e. soil, plants, etc.) in pollutant removal and volume reduction. This project is designed to assist MS4s in the assessment of their stormwater BMPs and the utilization of these BMPs in watershed TMDL analyses. Objective B of this project focuses on the infiltration performance of low impact development (LID) practices. The infiltration capacity testing developed for rain gardens (Asleson, et al. 2009) was to be refined, altered and expanded for other types of LID practices including infiltration basins and trenches, vegetative swales and filter strips. The Modified Philip Dunne (MPD) infiltrometer is implemented as a low-effort, low-cost method to determine saturated hydraulic conductivity, a predictor of infiltration capacity. This infiltration tests have been performed on rain gardens, infiltration basin, swales and turf areas.