MCM 5: Post Construction Stormwater Management (PCSWM)
In natural systems, most rain and snowmelt infiltrates into the ground to provide nourishment for vegetation or to replenish ground-water supplies. During heavier storms rainwater flows downstream into creeks and streams. Land development changes this natural cycle. Constructing homes, businesses, and parking lots prevents infiltration. Instead, stormwater runoff is collected and discharged off-site via a series of inlets, pipes, and swales. This concentration of flow scours stream banks, causes excessive erosion, and degrades stream channels.
West Lampeter Township has incorporated water quality measures into the most recent Stormwater Management Ordinance that requires all new land development projects with over 1,000 sf of impervious surface area to infiltrate and/or harvest the first one-inch of rain. While this will provide water quality benefits in future projects, it does not address the stormwater management facilities in existing neighborhoods and business properties. To improve water quality in these developments, West Lampeter Township will promote projects to retro-fit traditional stormwater infrastructure with “green” infrastructure projects.