In early 2019, Upstream PGH (then known as the Nine Mile Run Watershed Association) asked CivicMapper to conduct a Phase 1 Hydrologic Study to characterize the hydrology of the Nine Mile Run Watershed and to identify at least 10 locations across the entire watershed where green stormwater infrastructure (GSI) would be most effective.

CivicMapper began this work by examining the usability of three GIS datasets: the 2017 Allegheny County QL2LiDAR dataset, the 2010 Urban Tree Canopy dataset, and the 3RWW Sewer Atlas data. Using these as a basis for the study, CivicMapper created derivative elevation and land cover data products, including a hydrologically corrected Lidar elevation dataset and derivative hydrologic flow lines. These data were then used to help identify 27 hydrologically significant locations that represented good potential for GSI implementation across the watershed. For each location, CivicMapper used its Peak Flow Calculator tool and map model to estimate the volume of water passing through each site and estimate the effect of various GSI on that location.

Results of this project were delivered in a series of reports and data sets: a Data Quality Memo, a set of data, tools, and models that could be used to further investigate the 27 sites and additional locations, and a Final Phase 1 Hydrology Report. This final report contained a summary of the methodology used to develop the hydrologic characterization of the Nine Mile Run Watershed, including location selection criteria, and details about the hydrologic model and the peak flow calculator tool. The report also contained individual datasheets for all 27 GSI sites that contained a map, basin statistics, and output data from the peak flow calculator tool.

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