Stormwater Regulations --
Now and in the Future 
In just two years, all current stormwater regulations
 must be implemented. Are you ready? 

Smaller municipalities and other agencies were brought under the stormwater regulations of the Clean Water Act three years ago. The five-year implementation cycle will be complete in 2008.

Road and street construction and maintenance are affected by the program's six goals:

• Initiate a comprehensive, independent analysis of stormwater treatment practices now in use.

• Develop a stormwater treatment practice assessment.

• Develop a draft assessment protocol that includes a decision tree to aid in deciding on treatment and monitoring.

• Test the assessment protocol on selected field sites.

• Collaborate with other agencies and groups to further develop the protocol.

• Begin outreach and dialogue with workshops and public forums.

These same agencies, as they work their way into using the regulations, can control costs by using low-impact-development practices for stormwater management.

What is LID?

Low-impact-development strategies let water infiltration occur as closely to the original area of rainfall as possible.

Landscaping, including soil placement and vegetation, can help reduce the need for expensive engineered runoff removal systems.

Designs need to include ways to avoid pollution from stormwater runoff — another reason for absorbing the moisture as quickly as possible.

Most pollutants get carried along in the first half inch of the storm. LID Systems need to include a buffer to filter the pollutants, particularly during this period. Several companies make retrofits for existing stormwater inlets to do this job, including AquaShield, Stormtreat Systems, Stormceptor, and Stormwater Management.

Best LID stormwater practices include:

• Reduction of the volume of runoff and decentralizing flows. This can be created with a series of smaller retention/detention areas that allow localized filtration rather than carrying the runoff to a remote collection area.

• Bioretention cells generally are made up of grass buffers, sand beds, a ponding area for excess runoff, planting soil, and vegetation. These provide storage for the water away from roadways and buildings.

• Grass swales can function as alternatives to curb and gutter systems, generally along residential streets or roads.

• Filter strips can be designed as landscape features and direct water into vegetation detention or sand filter areas.

• Directing stored water to localized detention cells where it can be used for dry-period irrigation.

On site

• LID site design elements include decreasing impervious surfaces that prevent natural filtration, such as:

• Reducing roadway surfaces and retaining more permeable land. Using longer, undulating roads that create more available lot frontage can reduce pavement needs and runoff at the same time. Shared driveways, landscaped detention islands within cul-de-sacs, or alternate designs for turn-around areas can be used.

• Permeable pavement surfaces can be built from a variety of materials, including traditional asphalt, concrete, gravel, or pavers. A permeable road or street lets water flow through, reducing or eliminating the need for stormwater structures.

• Vegetative systems create a lightweight permeable surface on an area, such as along streets.

LID costs

Use of engineered grass swales and other LID methods may cost only 35 to 50% of more conventional controls.

Even so, large or highly industrialized cities may have pollutant levels that can't be handled by LID filtration. And, local regulations may need to be overhauled to allow use of LID methods.

In Minnesota

Minnesota is a good example of a state that has provided municipalities with help in meeting stormwater regulations. Assessment protocol progress is a key part of their program, with a project team working with the University of Minnesota Extension Services offering help to consultants as well as municipal and county engineers. The team drafted an Assessment Protocol Outline last year.

Their program will monitor various stormwater management practices as the protocol continues to be developed. Work will include assessment of three underground proprietary devices for the Local Road Research Board.

Input sessions last year were geared to several objectives:

• To determine the priority of stormwater practices to have assessment protocols developed for and to be monitored.

• To determine specific performance information to be known as priority stormwater practices.

• To discover opportunities to partner with on-going stormwater practice installation and monitoring activities.

• To gather lessons learned from on-going and past water-quality monitoring efforts.

Revised stormwater rules now require stormwater permits for cities over 10,000, or over 5,000 if the municipalities are located within a half mile of outstanding value resource water or impaired water.

Small municipalities must develop a Stormwater Pollution Prevention Program that covers:

• Public education and outreach.

• Public participation/involvement.

• Illicit discharge detection and elimination.

• Construction site runoff control.

• Post-construction site runoff control.

• Pollution prevention/good housekeeping.

Wading through regs

Stormwater regulations are complicated and likely to become more so.

Dr. Stephen J. Souza at Princeton Hydro in Ringoes, New Jersey has developed an introduction to help municipal officials understand the new regulations.

“Over 60% of existing water quality problems are the result of non-point source pollution linked to stormwater runoff,’ Souza says. Stormwater runoff can degrade the quality of wetlands, surface water, and groundwater. This impacts the ecological, recreations, and aesthetic attributes of these resources. Degraded surface and groundwater can cause or lead to human health impacts.

Use of a control program is especially needed in developed areas where storm  runoff is about 55% of the total downfall compared to 10 to 15% runoff on undeveloped land.

“States were required to adopt municipal stormwater management rules by March of 2003,’ Souza says. The rules pertain to MS4s — Municipal Separate Storm Sewer Systems. The intent of the new rules is to improve the quality of surface waters, letting them meet designated uses.

Rules affect both large and small municipalities, but requirements differ. Both Tier A (large) and Tier B (small) cities must develop and adopt stormwater management plans, develop and adopt a stormwater management ordinance, conduct public education, and implement additional measures as needed.

The regulation timetable is full implementation by 2008.

Construction site regulations especially affect agencies and erosion control practices must be enforced at all construction sites, Souza says. Pollution prevention measures must be implemented at construction sites. The practices apply to disturbances of greater than one or more acres of land. The regulations do not do away with the need for county permits for disturbances of 5,000 square feet or more.

After construction, continued stormwater measures include adoption of a stormwater management plan, adoption and implementation of a stormwater management ordinance, ensured maintenance of stormwater best-management practices, implementation of state stormwater management regulations, and meeting design standards for storm drain inlets.

Source control activities required include pollution prevention, salt and sand storage, and road erosion control.

For a copy of Souza's presentation, e-mail him at Ssouza@princetonhydro.com.

Ways to Reduce Road Runoff

According to the National Education for Municipal Officials, some basic steps will help reduce road runoff:

• Avoid disturbing natural drainage patterns.

• Vary the pavement according to the proposed use, keeping narrower widths (with less runoff) in slow speed zones, for instance.

• Incorporate alternative stormwater management techniques such as vegetated swales.

• Mandate curb and gutter drainage with a minimum distance between catch basins.

• Assure minimum lot widths and side yards produce roads that are built for the minimum required pavement width needed to support projected traffic volumes.

• Minimize the number and width of cul-de-sac roads.

• Minimize turnaround radii on cul-de-sacs.

• Use permeable pavement surfaces where possible.

Source: University of Connecticut.

Top 12 Stormwater Practices Needing Further Assessment

1. Rain gardens.

2. Grass channels and swales.

3. Constructed bioretention systems.

4. Porous pavement and permeable pavers.

5. Stream and shoreline buffers.

6. Infiltration basins.

7. Proprietary sediment removal devices.

8. Erosion repair.

9. Street sweeping.

10. Multi-cell ponds.

11. Surface flow filters such as buffer strips.

12. Wet ponds.

Source: Minnesota Pollution Control Agency.

Reprinted from Better Roads Magazine
June 2006