Watershed Symposium 2018 has ended
Welcome to the official website of the 12th Annual Salt Lake County Watershed Symposium, November 14-15, 2018!  Free and open to all, the Symposium encourages a comprehensive review of the current state of our watershed while creating learning and networking opportunities for a broad array of stakeholders. Sessions cover a broad range of topics on water quality and watershed issues with local, regional, and national relevance. Hosted annually by Salt Lake County Watershed Planning & Restoration.

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Thursday, November 15 • 11:35am - 12:15pm
Modeling the Effect of Green Infrastructure Implementation In the Red Butte Creek Area

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Modeling the Effect of Green Infrastructure Implementation In the Red Butte Creek Area

This presentation provides an evaluation of the performance of the stormwater modeling package WinSLAMM in Northern Utah where it has not been validated before for the prediction of stormwater runoff and pollutant loading and the effects of various green infrastructure (GI) implementation strategies on stormwater impacts to Red Butte Creek.

Full Abstract
WinSLAMM is water quality model used for modeling stormwater runoff and pollutant concentrations from various urban land use sources. One strength of the model is that it can be used to evaluate the impact of green infrastructure implementation on runoff quantity and quality. However, it has been developed and tested in regions with climatic and topographic characteristics very different from that observed in Northern Utah. This study provides an evaluation of the performance of WinSLAMM in a region in which it has not been validated to date for the prediction of stormwater runoff and pollutant loading and the effects of various GI implementation strategies on stormwater impacts to Red Butte Creek. Runoff volumes and pollutant loads for Total Suspended Solids (TSS), Total Phosphorus (TP) and Dissolved Phosphorus (DP) for a series of events from 2015 to 2017 were calculated for six study areas in Northern Utah. Measured data were compared to model outputs and results indicated that the model performed poorly when default parameters where used. Thus, the model required calibration of runoff coefficients and pollutant concentrations using locally measured input data. Once calibrated, the model performed well for TSS prediction but poorly for TP and TDP unless these nutrient concentrations were predicted using locally measured TP/TSS and TDP/TSS relationships. With locally calibrated runoff parameters and locally normalized nutrient loadings as a function of storm depth, three scenarios of green infrastructure implementation (various GI system implementation of 10%, 50% and 100% of connected imperious surface) were analyzed for two subbasins within the Red Butte Creek watershed area. For the 10% GI Implementation case, treating streets produced the greatest TSS reduction, while treating roofs produced more volume reduction. For the 50% GI Implementation scenarios, runoff reduction was similar no matter the surface type being treated. However, there was a great difference in TSS reduction, with implementing GI for streets producing the greatest particulate solids reduction, followed by parking lots and then by roofs. If 100% of the impervious surface was treated by GI in these two Red Butte Creek subbasins a greater than 80% runoff volume reduction, and more than 70% TSS, TP and TDP pollutant load reduction were predicted. The decision of what GI techniques to implement and in what combination is driven by overall reduction objectives, and the contributing surface types within the drainage area. Once calibrated to local flow and pollutant loading conditions, WinSLAMM is a useful tool to evaluate stormwater management options to meet specific performance and/or compliance goals. With participation in this workshop, attendees will learn that all GI systems do not provide equal pollutant removal and runoff reduction performance, and that with locally generated input data, WinSLAMM provides managers with an effective tool to develop optimal implementation plans for stormwater management in their watersheds.

avatar for R Ryan Dupont

R Ryan Dupont

Professor, Utah State University
Dr. Dupont is a Professor of Civil and Environmental Engineering at Utah State University and has more than 35 years of experience teaching and conducting applied and basic research in environmental engineering at the Utah Water Research Laboratory at Utah State University. He received... Read More →

Thursday November 15, 2018 11:35am - 12:15pm MST
Lower Level - Ballroom C Utah Cultural Celebration Center, 1355 W 3100 S, West Valley City, UT 84119