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Full text release has been delayed at the author's request until June 01, 2024

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Performance Models for Manufactured Stormwater Best Management Practices with Sedimentation and Filtration in Series

Mallikarachchi, Thanuja D.
http://orcid.org/0000-0002-4531-3225
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1547131754278262

Abstract Details

2019, Doctor of Philosophy (PhD), Ohio University, Civil Engineering (Engineering and Technology).
Best management practices (BMPs) are used to treat runoff from highways prior to being released to surface water bodies. While DOTs across the nation use various forms of BMPs for runoff treatment, the need for a successful BMP for urban highways has not been fulfilled. The exfiltration apparatus (ExA) is a manufactured best management practice with a small foot-print that is meant to catch and treat urban stormwater runoff. The ExA treats runoff with a sedimentation unit and filtration units that are connected in series. The ExA holds structural similarity to some other urban BMPs. The ExA’s flow and particle operation had not been modeled previously. Thus, correct flow and particle routing through the device were unresolved. Two lab studies were conducted to evaluate the hydraulic response and evaluate the particle routing processes of the exfiltration apparatus. In Phase I of the lab study, a scaled-down prototype of the ExA was operated with clean tap water, and head loss data over the ExA components were collected for varying infiltrating flows. The ExA underdrain design did not restrict the flow, and the pressure head build up was from the geotextile layer. Average infiltration capacity for the downsized ExAs prototype ranged from 11.6 ~ 12.53 gpm (0.731 – 0.791 dm3/s) for loosely packed media which translated to a catchment area of 0.122 acres for the full scale ExA. Reynolds number evaluation revealed that the system operated under transient to turbulent flow conditions and warranted non-linear flow modeling. A stage-discharge relationship valid for fully submerged media and subjected to downward flow was derived. The ExA retained particles within the sedimentation volume and subsequent filter media layers. In Phase II of the study, the ExA prototype was subjected to flow consisting of soluble dyes, to evaluate the flow detention, and coarse and fine particles to evaluate sedimentation and filter processes. Rhodamine B dye testing revealed that in pristine condition, at full infiltrating capacity at 11.6 gpm, the ExA had a short hydraulic retention time of 47 s. Particle studies revealed that sand (150-400 µm) particles were mostly retained within the sedimentation volume. Fine particles reached the filter layer and the ExA clogging was observed during the first fine particle test. Clogging was in the lower portion of the sand layer: thus, the full media would need to be replaced to recover the loss of vertical conductivity. Based on laboratory test observations the following BMP alterations were recommended: 1. Minimize sediment scour and fine particle reaching the media layers by measures such as minimizing the orifice size of the corner dome orifices, 2. Allow longitudinal flow in the media layers to achieve partial operation after vertical clogging. Kalinske’s sedimentation model fit the data better than the Camp’s model because it included both vertical and horizontal turbulence. Quiescent removal equations were recommended for calculating removals as vertical turbulence did not affect settling negatively. The vertically clogged sand layer had filtration rates comparable to cake filters, while the aggregate layer (with particle deposits) had filter coefficients comparable to depth filtration.
R. Guy Riefler (Advisor)
262 p.
Civil Engineering; Environmental Engineering
Manufactured BMPs; Geotextile filters; Urban stormwater runoff treatment; and BMPs with Sedimentation and Filtration

Recommended Citations

Citations

  • Mallikarachchi, T. D. (2019). Performance Models for Manufactured Stormwater Best Management Practices with Sedimentation and Filtration in Series [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1547131754278262

    APA Style (7th edition)

  • Mallikarachchi, Thanuja. Performance Models for Manufactured Stormwater Best Management Practices with Sedimentation and Filtration in Series. 2019. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1547131754278262.

    MLA Style (8th edition)

  • Mallikarachchi, Thanuja. "Performance Models for Manufactured Stormwater Best Management Practices with Sedimentation and Filtration in Series." Doctoral dissertation, Ohio University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1547131754278262

    Chicago Manual of Style (17th edition)

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© 2019, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.