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New RCWD rules

Strengthening Rice Creek Watershed Rules

A key element of protecting water quality is to effectively manage stormwater. Managing stormwater is critical to protecting water quality because roads, rooftops and other impervious surfaces are a major conduit of polluted stormwater to lakes and streams. In many communities, these surfaces carry stormwater runoff to storm sewer systems and into nearby lakes and streams. By infiltrating stormwater on new developments and roads, stormwater “plumbing” is disconnected and most stormwater infiltrates before reaching storm drains. While you can’t infiltrate all rainfall, these rules aim to infiltrate between 0.08 inches and 2.8 inches of rainfall from storms.

  • The first inch or so of rain in any storm (often called the “first flush”) contributes most of the stormwater pollution to nearby waters. Infiltrating this “first flush” is vitally important to the health of lakes and streams.
  • About 90% of all storms are less than 1.0 inch. These new rules help infiltrate almost 90% of all storms in the area, and with it prevent most stormwater pollution.
  • This can be achieved in a fair, cost-effective manner. Technology has come a long way in the last 10 years, and will only improve over time.
  • The physical characteristics of the watershed, with sandy soils and comparably wide rights-of-way, make a 1-inch rule achievable.
  • Lastly, the potential benefits of decreased water pollution could make a big impact on the quality of lakes and streams throughout the watershed. Property values, recreational opportunities and quality of life are all closely tied to the health of our lakes and streams.

The new rules

FMR focused our energy on encouraging the passage of two key infiltration rules governing stormwater infiltration and roads.

Rule C, Section 5(b): Stormwater Infiltration

Background

New developments create impervious surfaces, which don’t allow rainfall or snowmelt to infiltrate (soak into the ground). This means that water flows off the site and into storm sewers, where it carries pollutants untreated into local lakes and streams. This rule requires new developments (and major redevelopments) to infiltrate most rainfall and snowmelt water on site, rather than funneling it all into storm drains (and into your lakes and streams).

The rule

Water Quality and infiltration BMPs must be sized to infiltrate and/or retain the runoff volume generated within the contributing area by a two-year (2.8-inch) storm under the developed condition … A site with soils classified as Hydrologic Soil Group (HSG) A or B must meet this standard through infiltration for at least that part of the site where A and B soils are present.

What it means

FMR strongly endorses the RCWD’s stormwater infiltration rules for new development and significant redevelopment. These rules reflect state-of-the-science best management practices and are an excellent step toward improving overall water quality. We feel that these rules

  • Are compatible with current technology and best management practices
  • Are a cost-effective method of long term water resource improvement
  • Represent necessary, incremental improvements that will help the watershed avoid large, expensive fixes down the road
  • Are the best long term options for protecting and preserving water resource health in the Rice Creek Watershed

Rule C, Section 5(f): The Road Rule

Porous Paving demonstrated.]

Porous paving systems provide a hard road surface while allowing rainwater to infiltrate into the ground below.

Background

Roads, like other impervious surfaces, carry stormwater untreated into storm drains and directly into nearby surface waters — polluting valued lakes, wetlands and rivers. New road development and some major road reconstruction projects will be required to infiltrate some stormwater beneath the road bed, rather than funneling it all into storm drains. This is referred to here as “the road rule,” and it has two parts:

  1. New road projects over a certain size must capture and treat the first 2.8 inches of rainfall — just like the stormwater infiltration rule above.
  2. Major road reconstruction projects over a certain size must include retrofits that will also capture and treat stormwater runoff. This doesn’t include resurfacing projects (“mill and overlays”), but when a road undergoes major reconstruction, this rule will apply. Its application depends on the type of road being reconstructed.
Project type Roadway classification Infiltration requirement
New road construction (≥1 acre of impervious surface) Arterial, county road or highway Standard for non-linear projects applies to runoff from new and reconstrutcted impervious surface.
Collector, subcollector or access Standard for non-linear projects applies to runoff from new and reconstructed imprevious surface and the directly connected impervious surfaces within the project corridor.
Road construction or new construction (≤1 acre impervious surface) Arterial, county road or highway Infiltration of 1.0 inches of runoff from the new and reconstructed impervious surface.
Collector, subcollector or access Infiltration of 0.8 inches of runoff from the new and reconstructed impervious surface and the directly connected impervious surfaces within the project corridor.
Rehabilitation or resurfacing All No new water quality or volume control requirement.

What it means

This “road rule” is critical to protecting water quality because roads are a major conduit of polluted stormwater to lakes and streams. In many communities, roads are used as plumbing to carry runoff to storm sewer systems and into nearby lakes and streams. By infiltrating water under the roads, the “plumbing” is disconnected and most stormwater infiltrates before reaching storm drains. Also:

  • The first inch or so of rain in any storm (often called the “first flush”) contributes most of the stormwater pollution to nearby waters. Infiltrating this “first flush” is vitally important to the health of lakes and streams.
  • This can be done in a fair, cost-effective manner. Technology has come a long way in the last 10 years, and will only improve over time. Several nearby watersheds already infiltrate 1.0-inch of rain off road surfaces.
  • The physical characteristics of the watershed, with sandy soils and comparably wide rights-of-way, make a 1-inch rule achievable.
  • Lastly, the potential benefits of decreased water pollution could make a big impact on the quality of lakes and streams throughout the watershed. Property values, recreational opportunities and quality of life are all closely tied to the health of our lakes and streams.