Construction Site Regulations
National Pollutant Discharge Elimination System (NPDES) Program
The NPDES Section of the Iowa Department of Natural Resources issues discharge permits under delegation of a federal program known as the NPDES (National Pollutant Discharge Elimination System) permit program. The NPDES program regulates wastewater and stormwater discharges directly to surface waters. The authority to issue NPDES permits rests either with a state or with the U.S. Environmental Protection Agency (EPA). The Iowa Department of Natural Resources was delegated NPDES authority in 1978.
Under Iowa’s NPDES program, all facilities that discharge pollutants from any point source into surface waters are required to obtain an NPDES or operation permit from IDNR. The permits require compliance with all federal standards, state rules, and state administrative code. The Iowa DNR issues three types of General NPDES Permits related to stormwater management.
- General Permit No. 1 (GP#1), Storm Water Discharge Associated with Industrial Activity
- General Permit No. 2 (GP#2), Storm Water Discharge Associated with Construction Activity
- General Permit No. 3 (GP#3), Storm Water Discharge Associated with Asphalt Plants, Concrete Batch Plants, Rock Crushing Plants, Construction Sand, Gravel Facilities
The IDNR has also issued individual stormwater permits to cities and universities under their MS-4 (Municipal Separate Storm Sewer System) program. Cities and universities are selected based on population, proximity to an urban area and/or discharge to an impaired waterbody. You will be contacted by the Iowa DNR if a MS-4 permit is required by your community. In all permits a Stormwater Pollution Prevention Plan is required.
Erosion controls are necessary on a construction site to prevent detachment and transportation of sediment particles on disturbed soils. Preventing erosion before soil is detached from the ground is the most effective method in preventing stormwater pollution.
Common erosion control practices include: compost blankets, mulching, temporary and permanent seeding, sodding, rolled erosion control products (RECPs), surface roughening, and vegetative filter strips. The most effective and cheapest erosion control, however, is to maintain as much existing vegetation on a site as possible.
The approved Stormwater Pollution Prevention Plan (SWPPP) for the construction site will list, in addition to other practices, required erosion controls and where they are to be located. Erosion controls must be inspected on a weekly basis to ensure they are functioning properly.
Sediment & Velocity Controls
Sediment controls are necessary to capture sediment that has been detached through different types of erosion (i.e. sheet and rill erosion, gulley erosion, streambank erosion, and wind erosion). Sediment controls are known as the “last line of defense” before sediment and other stormwater pollutants reach Iowa’s rivers, lakes, and streams. Similarly, velocity controls attempt to slow the flow of stormwater in areas of concentrated flow, promote infiltration and settling of particles.
Common sediment and velocity controls practices include inlet protection, sediment basins and traps, flocculents, check dams, wattles and filter socks, silt fences, rip rap, rock chutes, and more. Selection of appropriate sediment and velocity controls will vary by site conditions. Controls must be inspected, and potentially repaired, weekly to ensure effectiveness.
Good Housekeeping Practices
Other than erosion and sediment controls, stormwater pollution can be prevented through proper site management.
Common best management practices for good housekeeping include a stabilized staging area, debris containment and secondary chemical containment, proper sanitary waste procedures, spill prevention, and compliant concrete washout facilties and wet saw cutting procedures.
One of the most common stormwater violations related to good housekeeping is sediment trackout from construction sites. An appropriately sized rock entrance is an effective method for removing sediment from vehicles prior to entering the roadway.
Contractors should refer to the Statewide Urban Design and Specifications (SUDAS) manuals for recommendations on siting, sizing, and materials used for good housekeeping practices. Division 11 of the SUDAS Specification Manual includes guidance for concrete washout, while Division 9 provides guidance for erosion and sediment controls.
Training for Erosion and Sediment Control Inspectors and Installers
The Iowa Stormwater Education Partnership conducts routine training opportunities for professionals who install and inspect erosion controls, sediment and velocity controls, and good housekeeping practices. More information on the training and certification program, titled “Iowa Certified Construction Site Pollution Prevention Inspector and Installer“, can be found under the training tab on this website.
In addition to a General Permit, construction, excavation or filling in streams, lakes, wetlands, or flood plains may require a Section 401 permit from either or both the Army Corps of Engineers and Iowa DNR. A Joint Application Form (Protecting Iowa Waters) shall be submitted to both agencies to begin the permit process for any of the following activities:
- Cutting the bank of a river, stream, or lake;
- Any excavation or dredging in a wetland, lake, stream or river;
- Channel changes or relocations (including stream straightening);
- Construction of any permanent dock, pier, wharf, seawall, boat ramp, beach, intake or outfall structure on a stream, river or lake;
- Placement of any fill, riprap, or similar material in a stream, river, lake, or wetland;
- Construction of a dam across any waterway;
- Placement of fill, construction of levees, roadways and bridges and similar activities on a floodplain, or construction of buildings on a flood plain; or
- Any construction on, above, or under all fee title lands and waters, dedicated lands and waters under the jurisdiction of the Natural Resource Commission (Commission) and managed by the Commission for public access to a meandered sovereign lake or meandered sovereign river; meandered sovereign lakes; meandered sovereign rivers; and sovereign islands (except those portions of the Iowa River and Mississippi River where title has been conveyed to Charter Cities).
Other Local Permits
Cities and counties throughout Iowa may issue permits related to stormwater activities for grading, construction site erosion and sediment control, post construction stormwater and floodplain management. Contact your local city or county for details on a local level. Relevant ordinances can be found in a city’s code of ordinance, or may be listed on the Communities tab of this website.