Fairfax City public works staff described a combined outfall restoration and sanitary sewer encasement project intended to reduce erosion, protect sewer infrastructure and generate pollution-reduction credits for the Chesapeake Bay cleanup.

"All of the watersheds in the city do drain into the Chesapeake Bay," Satoshi Ito, public works program manager, said. He told the briefing the Chesapeake Bay Preservation Act and the city's municipal stormwater permit require jurisdictions in the bay watershed to reduce pollutant discharges.

Ito said the project area includes a cul-de-sac at the end of Old Robin Street and outfalls discharging stormwater from Bluecoat Drive into a tributary of Accotink Creek. City crews plan to modify eroded outfall channels so they are less prone to erosion and to encase a nearby sanitary sewer line in concrete to reduce the risk of damage and a potential sewage discharge to the stream.

"When we reduce erosion, we reduce sediment and the pollutants that are associated with it," Ito said, explaining that sediment, nitrogen and phosphorus are the three pollutants of concern for the bay and that reductions are measured in "pounds per year," with each pound representing a credit toward a jurisdiction's required reductions.

Ito said the outfall projects require some vegetation removal during construction but include landscaping plans to replant affected areas. He described combining the outfall restoration with sewer encasement work as a method to minimize disturbance by using common access points.

No formal vote or funding appropriation was taken during the briefing. Ito described the work as a cost-effective way to gain pollutant-reduction credits compared with larger stream-restoration projects and identified the projects as one option staff will pursue to meet permit obligations.