The DWW (Drainage and Waste Water) GSI (Green Stormwater Infrastructure) layer consists of line and polygon representations of the following features: Swales (biofiltration, bioretention, biofiltration/bioretention, and conveyance) are generally shallow depressions with a designed mix of soil and plants which break down pollutants through natural processes while reducing runoff. Permeable pavement is a paving system which allows rainfall to percolate into an underlying soil or aggregate storage reservoir. Underdrain piping systems are provided to prevent prolonged ponding of stormwater or to collect and convey water to another facility. Rain gardens are less engineered systems that are designed to mitigate water from the sidewalk only and have two inches or less of ponded depth. The drainage structures represented in the GSI points are not all unique to GSI, however, they are specifically part of SPU GSI projects.,

The RainWise program helps eligible property owners manage stormwater by installing rain gardens and/or cisterns on private property. The program is jointly funded by King County and SPU as part of the effort to manage 700 million gallons of storm runoff using green infrastructure by 2025. Property owners must live in selected Combined Sewer Overflow basins to be eligible.

While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m2, lined sections that direct all infiltrate into 5.7-m3 tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP and PC, and this was attributed to the high pH in PA infiltrate possibly causing rapid precipitation of orthophosphate with metal cations. Orthophosphate was exported from the PICP and PC, as evidenced by the significantly larger infiltrate concentrations compared with influent sources of rainwater and runoff. This dataset is associated with the following publication: Brown , R., and M. Borst. Nutrient Infiltrate Concentrations from Three Permeable Pavement Types. JOURNAL OF ENVIRONMENTAL MANAGEMENT. Elsevier Science Ltd, New York, NY, USA, 164: 74-85, (2015).

,

These are quality-assured time series datasets from weather stations and runoff volume monitoring infrastructure, Cleveland OH. This dataset is associated with the following publication: Shuster, W., and R. Darner. Hydrologic Performance of Retrofit Rain Gardens in a Residential Neighborhood (Cleveland Ohio USA) with a Focus on Monitoring Methods. U.S. Environmental Protection Agency, Washington, DC, USA, 2018.

Surface drainage points are structures that help direct rainwater in the City’s sub-surface pipe drainage system. The informal drainage system makes up nearly one-third of the City of Seattle footprint. This layer displays connected surface drainage points, regardless of ownership, that cannot be found in other layers. For example, Catch Basins, Junction Boxes, Sandboxes, and Inlets are not included. The data source is DWW.surface_drainline_pt_pv with the following data query: SDP_LIFECYCLE_TEXT IN ( 'Connected' , 'Unknown' , 'Temporary' ,'To Be Connected', 'Under Construction', 'Provisionally Connected', 'Proposed', 'Abandoned', 'Abandoned Temporary', 'Removed') AND SDP_FEA_TYPE_TEXT IN ( 'Area Drain;Area Way;Driveway Drain' ,'Cleanout', 'Flow Control MH' , 'Infall' , 'Maintenance Hole' , 'Overflow MH' , 'Other' , 'Rubber Coupler' , 'Reducer' , 'Surface Cleanout' , 'Sedimentation Chamber;Sand Catcher;Sand Trap' , 'Stand Pipe' , 'Weephole', 'Catch Basin MH', 'Vault', 'Underground Injection Cell; Drilled Drain'),

This layer indicates which areas contribute sanitary and storm water flow to a CSO overflow point. Areas are broken down by NPDES Outfall Number. The data source is DWW.cso_basin_plgn_pv. The layer continues to be updated as new information about the CSO system becomes available and as modifications to the system are completed. The boundaries in this layer were created and updated for purposes of developing a hydrologic and hydraulic computer model. The model was used to estimate CSO control volumes and develop CSO control alternatives. Estimation of control volume and alternative analysis did not require a parcel level of detail, so it is expected that the boundary is not always correct at the parcel level. In addition, the CSO basin boundary shapefile reflects both the sewer basin AND the drainage basin tributary to the overflow point, and these two basins do not always line up cleanly. This layer reflects the best compromise between the two boundaries.,