Issue: October, 2009
Author: Magdalene M. Allely
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Storm Water Permitting in Wyoming Construction Sites
What is storm water and why is it important?
Storm water is precipitation (usually in the form of rain or snow) that contacts impervious surfaces like driveways, parking lots, sidewalks and streets. This definition sounds rather innocuous until you consider that these impervious surfaces act as streamlined conduits for storm water to pick up and carry debris, chemicals, dirt and other pollutants directly to lakes, streams, wetlands or rivers.
Storm water has become more of an issue over the past several decades as neighborhoods replace ranch or farmland; as shopping centers and business parks sprout up in previously open fields. More neighborhoods and shopping centers means more cement and asphalt. Instead of percolating into the soil, the water encountering these hard surfaces now collects and joins with other water to form a formidable force for carrying a myriad of pollutants.
The implications of storm water are wide spread. In Wyoming, the construction industry provides us with some conspicuous examples as to why storm water needs to be controlled and managed. It is typical for construction sites to be cleared of stabilizing vegetation so that construction may commence. Preparing a construction site results in a wide swath of bare soil. When a storm event occurs and the site is exposed to rain and the effects of gravity, the water will carry the soil, and any other contaminants, from the site. The migration of soil and other contaminants off the construction site can cause unintended consequences.
Polluted storm water is a significant source of water pollution in Wyoming. Polluted storm water requires communities to treat their drinking water thereby increasing the cost. Polluted storm water also negatively impacts receiving streams. Sediment covers up fish habitat and household fertilizers can cause excessive algae growth thereby decreasing the oxygen available in the water for fish.
It should be noted that construction sites are not the only potential contributors of pollutants to storm water. Together with oil and gas and industrial sites, the average citizen can have negative impacts too. Storm water carries pesticides and fertilizers from our yards, pet waste, lawn clippings, detergents from car washes, oil from streets and driveways, and garbage into the storm water system. In many, if not most, storm water systems throughout the state, the storm water goes directly to a receiving stream without being treated. These same receiving streams are a source of drinking water for many cities and towns.
Storm water is an example of “non-point source pollution.” This term is a catch-all phrase for water pollution that does not come from a “point-source,” that is, a source that has a discernable, confined and discrete conveyance like a pipe, ditch or channel. Non-point source pollution can be difficult to treat and the goal of federal and state storm water permitting programs is one of prevention. If the amount of pollution coming into contact with storm water can be decreased, the need for treatment will likewise be decreased.
Storm Water Permits - Construction Sites
Managing storm water not only implicates environmental concerns, it implicates legal ones too. Federal regulations require states to implement permitting programs geared toward improving the quality of storm water in order to protect lakes, streams, rivers and wetlands.
The federal Clean Water Act and the Wyoming Water Quality Rules and Regulations require operators of construction sites that disturb an acre or more of land to obtain coverage under a storm water permit. In Wyoming, the Department of Environmental Quality implements the storm water program under the Wyoming Pollutant Discharge Elimination System (WYPDES). (The Federal Environmental Protection Agency is the permitting authority on tribal lands.)
There are two types of storm water permits for construction activities: Small and Large. A Small Construction General Permit (SCGP) covers projects that disturb between one and five acres of land. Disturbances that are smaller than one acre are not necessarily exempt and may be required to be covered by a permit if they are part of a larger “common plan.”
An example of such a “common plan” is when a developer has a four acre subdivision and an individual builder buys a half-acre lot. Even though the builder’s lot is less than one acre, the builder must apply for coverage under the SCGP because his half-acre lot is part of a common plan which disturbs more than one acre.
A Large Construction General Permit (LCGP) covers projects that disturb five acres or more. Disturbances that are less than five acres of land may still be required to be covered under a large permit if those acres are part of a “common plan.”
An example of such a “common plan” is when a developer has a ten acre subdivision and an individual builder buys a half-acre lot. Even though the builder’s lot is less than one acre, the builder must apply for coverage under the LCGP because his half-acre lot is part of a common plan which disturbs more than five acres.
Coverage under either the SCGP or the LCGP includes all areas of soil disturbance, storage and staging areas, construction equipment, and asphalt and concrete manufacture. The permits do not authorize the discharge of wash water or produced water, nor do they authorize ground water dewatering or hydrostatic test water from pipelines. Such discharges are considered to be “wastewaters” and require a separate permit if discharged to surface waters of the state.
The key component of either the small or the large permit is the Storm Water Pollution Prevention Plan or SWPPP. The SWPPP requires permittees to formulate a plan to control and manage storm water run-off on a particular site. Specifically, all SWPPPs must describe how exposure of pollutants to storm water will be prevented, incorporate a plan to minimize transport of pollutants off-site, and utilize Best Management Practices, or BMPs. BMPs serve to keep pollutants on the construction site and out of surface waters and storm drains.
The SWPPP is a requirement of the permit and is enforceable as such. If the BMPs in the SWPPP are ineffective, they must be modified or replaced, and the SWPPP must be updated. All BMPs must be monitored at least once every 14 days and within 24 hours after any storm event of ½" or more.
There are a wide variety of BMPs to consider and each site will utilize different BMPs depending upon the unique circumstances of the site. Factors that contribute to choosing appropriate BMPs include topography of the land, size of the disturbance, and the nature of the potential pollutants. A BMP that is critical to one site might not even be a consideration at another.
A successful BMP is one that is used in the correct location, is the correct size and type for the expected flow, and is installed and maintained in accordance with the manufacturer’s specifications. In determining the appropriate BMP for a particular site, consideration must be given to unintended consequences. Improper BMPs can result in flooding of the site or neighboring property, unexpected erosion or washout and soil deposition in unintended or inconvenient areas.
You have likely seen many BMPs in action as you drive around town or on the interstate. It is common to see bales of straw in borrow ditches along roadsides. These bales slow the flow of storm water and allow sediment and other contaminants to precipitate out. Similarly, much of the landscaping that is part of new construction not only provides an attractive landscape, but also functions as an effective BMP by slowing and filtering storm water.
Once construction at the site is stabilized or complete, the operator may file a Notice of Termination wherein he or she certifies that any disturbed soils have been stabilized to the extent necessary to ensure that storm water runoff from the site will not cause a violation of Wyoming water quality standards.
The Wyoming Department of Environmental Quality has a comprehensive website dedicated to storm water permitting and both the small and the large permits can be downloaded by visiting deq.state.wy.us/wqd/WYPDES_Permitting/WYPDES_Storm_Water/stormwater.asp.
Magdalene M. Allely is an associate in the law firm of Hageman & Brighton, P.C., which focuses its practice on water and natural resource issues. Ms. Allely is licensed in Wyoming and Colorado.
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