Stormwater Management

Stormwater Management in Dover

What is Stormwater?

Stormwater is rainwater or meltwater that travels across rooftops, roads, parking lots and other impervious surfaces.

This is where it becomes a problem!

As stormwater passes over these surfaces it picks up oil, heavy metals, chemicals, road salt, and nutrients before ending up in local surface waters.

According to the New Hampshire Department of Environmental Services:
On undisturbed sites, much of the stormwater is intercepted by natural ground cover or is absorbed into the ground. Land clearing and development reduce the capacity of the land to absorb rainwater and snowmelt, which leads to more water flowing over the land and into surface waters.

What is Stormwater Management?
Stormwater management is the method of directing rainfall toward a treatment area, an appropriate body of water, or an identified outfall. Traditionally stormwater has been treated as a problem that needs to be exported from the property as quickly as possible. When exported from a site it runs over many different surfaces and into surface waters.

Unable to handle the increased water volume and pollutants, these waterbodies often experience eroded banks, loss of habitat and aquatic life, and increased flooding and property damage. We now understand that stormwater needs careful management onsite to avoid flooding, pollution, and water shortages which can negatively affect the City of Dover and its residents.

Historically, stormwater in Dover was managed through the use of an underground storm sewer system and direct outfalls to surface waters. The existing stormwater infrastructure is a mix of new structures installed as part of development during the last 25 years, and very old structures and pipes that served as a combined sewer system until the 1970’s.

However, extreme rain events may overwhelm this type of municipal infrastructure. When thishappens excess stormwater impacts the sanitary sewer system that conveys wastewater from residential and commercial structures to the wastewater treatment plant. According to the Dover Master Plan, even today the City experiences significant amounts of infiltration
into the sewerage treatment system during periods of heavy rain.

Using Low Impact Stormwater Management Practices in Dover

In developed areas roofs, decks, patios, pavement, and other impervious surfaces prevent stormwater from soaking into the ground.

Using low impact stormwater management practices involves retaining as much stormwater as possible on the property rather than letting it run into storm drains. This can help keep harmful volumes of stormwater and pollutants out of our surface waters while recharging Dover’s groundwater supplies. This reduces the impact on natural resources and contributes to Dover’s future sustainability as a community, and as part of the Seacoast Region.

This is accomplished by conserving forests and other natural areas, and stormwater controls that retain runoff such as:
Rain Barrels – capture rainwater and store it for use later.

  • Rain Gardens – landscaped areas designed to capture and filter stormwater.
  • Dripline Trenches – control erosive runoff from rooftops.
  • Dry Wells – collect and infiltrate runoff from downspouts.
  • Infiltration Steps and Trenches – built to slow and infiltrate runoff.
  • Paths and Walkways – direct foot traffic and prevent soil erosion.
  • Water bars – intercept runoff to prevent erosion.

National Pollutant Discharge Elimination System (NPDES) Permit Approval

Municipal Separate Storm Sewer Systems (MS4) Permit Year 1 Plans

Municipal Separate Storm Sewer Systems (MS4) Permit Year 2 Plans

Municipal Separate Storm Sewer Systems (MS4) Permit Year 3 Plans

Municipal Separate Storm Sewer Systems (MS4) Permit Year 4 Plans