TELR

Pollutant load removal is estimated separately for structural BMPs and non-structural BMPs. Structural BMPs’ reduction performance is estimated by identifying critical parameters such as existing condition, maintenance, and deterioration that would contribute to a BMP’s performance. The effectiveness of a BMP is then applied to source contributions to evaluate its load reduction.

In terms of non-structural BMPs, the swTELR focuses on implementation on impervious surfaces (e.g. paved roads) due to it being an urban stormwater model. The program first measures a watershed’s “runoff neutrality”, or parcel condition, to estimate how much precipitation is leaving a specific parcel of land. It also calculates a “road condition” value that determines the amount of deterioration a road has upon the target land use. The swTELR utilizes existing datasets from visual observations of roads to create a translation of road condition value to total suspended solid (TSS) characteristic runoff concentration, with figures found in their technical documentation showing that a lower road condition score leads to a higher runoff concentration. Existing tables of values with runoff neutrality and road conditions in the documentation allow users to identify their land use and conditions that correlate to an estimation of load removal amounts.

The swTELR prompts two categories of inputs for the user: catchment parameters such as size (acres), discharge points, land use distribution, imperviousness, soil type, etc; and BMP parameters both structural and non-structural such as location, type, removal/performance effectiveness. Catchment input values are accessible using the mapping procedures of their target location in 2NDNATURE software found in the swTELR program. BMP input values can be accessed using a database of values also in connection with swTELR, the 2N Rapid Assessment Methods (BMP RAM) database.

Results are in the form of visual tables, charts, and maps as swTELR is spatially based. A drop-down menu on the left of each graphic window allows for the user to pick and choose in color code what kind of data is visible on a figure, e.g. choose to color in catchments in watershed with high surface water runoff and leave rest of map in greyscale. Output charts may include, for example, a yearly summary of runoff load reductions, or a chart that shows water quality improvement over time.

• Tool is appropriate for planning phase and implementation phase of stormwater program.
• The model provides runoff and pollutant load reduction estimates
• Historic rainfall data from various precipitation zones within California are preprocessed and built directly into the model
• The user inputs BMP parameters using the BMP RAM and therefore will likely require some work to translate existing databases into BMP RAM input format
• The model is spatially distributed with an explicit accounting of input factor variation and BMP locations.
• Model is based on rainfall-runoff simulation only – no groundwater, snowmelt, point sources, etc
• Municipal use requires annual license fee to authorize usage of software

• Purchase of swTELR includes additional services of software maintenance, data security, user support and troubleshooting
• Future updates to the tool will bring “ROAD” Rapid Assessment Method implementation (Road RAM), which will monitor and record data for road conditions to more accurately model street sweeping and road pollutant control effectiveness.
• Future updates will also bring Trash RAM to track parcel and road condition with respect to trash accumulatio