Yelm Stormwater Utility Mapping

In 2016 the City of Yelm, Washington completed a Stormwater Management Plan funded and approved by the Department of Ecology (DOE) and the Yelm City Council. The plan included a gap analysis which identified an urgent need to inspect and map the city’s stormwater utility system, both public and private. Many system features were either unknown or missing critical information, such as pipe size, flow direction and capacity, invert elevations, and outfalls. Due to Yelm’s anticipated population growth, this data was necessary to migrate into an NPDES Phase 2 program. 

FLO used industry standard Geographic Information Systems (GIS) and high-accuracy global positioning system (GNSS) technologies to accurately capture the City’s managed stormwater infrastructure assets and private stormwater assets. The project included collecting, converting, and creating stormwater infrastructure data to incorporate into the City’s GIS database and supplemented by a comprehensive data attribution project using as-builts, resulting in complete GIS coverage of all stormwater systems. FLO delineated all stormwater drainage basins based on LiDAR data, inlets, and stormwater pond information.

The data FLO provided filled the knowledge gaps with complete data that improved the inspection and mapping of their public stormwater conveyance system and prepared the City for the next phase of their stormwater management regulatory requirements. The City now has more comprehensive data to coordinate with private stormwater facilities owned by local Homeowners Associations and businesses regarding private stormwater maintenance needs and regulatory requirements. The data underpins the City’s capital improvement planning for repairs, replacements, and retrofit needs within their collection, detention, and water quality facilities. It also helps them meet the regulatory needs due to increasing population growth.