The Sumner City Council met for a study session Jan. 25 to discuss changes in stormwater system development rates to connect to the city’s sewer and stormwater systems.

The stormwater utility fund is partially replenished by revenue from system development charges and pays for creating a system including storm drains, pipes, storage ponds and treatment systems. Other revenue comes from monthly rates, which are not changing.

City Administrator John Doan stated the demand on the stormwater utility increases not only because of the need to handle more quantity but also due to environmental requirements. Resetting the system development charge (SDC) will result in a healthier fund.

A system development charge is based on the amount of impervious surface created during the construction process.

Surfaces such as asphalt and concrete prevent water from seeping into the ground and are therefore impervious. Because the water runs off the surface it requires more pipe for the water to travel through. Due to the cost of collecting the water, a higher cost is imposed for the creation of impervious surfaces.

The development charge is applied only to creation of impervious surface area and is a one-time charge.

The current system development charge is $2,493 per equivalent service unit (ESU). A single-family home equals one ESU and a duplex is 1.5 ESUs. The city estimates there are 6.12 ESUs per acre of industrial area.

The change in the size of an ESU is the result of the city collecting the data on the average of recent family homes to determine a recommended increase of ESU value from 2,400 square feet to 3,100 square feet of impervious surface.

The stormwater charge would now be $2,338 per ESU for single-family homes, duplexes and multi-family, institutional, commercial and industrial developments.

FCS Group, which advised the city on the matter, recommended Sumner apply higher ESU values in calculating, which actually reduces charges.

In addition to reducing charges for single-family homes, the new cost assessment more fairly allocates costs between residential and commercial properties and rewards low-impact development.

Reach Chaz Holmes at cholmes@courierherald.com or 360-802-8208.