EPA Revises Construction–Related Stormwater Program to Set Discharge Limits and Monitoring Requirements

On December 1, 2009, the United States Environmental Protection Agency published regulations that will serve to add substantial new nationwide requirements and liability exposures in connection with stormwater runoff from construction sites involving 10 acres or more of disturbed area at any one time.

Numeric Discharge Limits

EPA has for the first time established a numeric discharge limit for construction-related stormwater runoff. That limit is based on the turbidity (i.e., murkiness) of stormwater discharged from a construction site during a storm event. The limit established is 280 NTU (nephelometric turbidity units) as the average of discharge samples taken over the course of a 24 hour period during a storm event. This discharge limit will apply to all storms of an intensity equal to or less than the worst storm event expected to occur at least once every two (2) years based on historical weather records for the area. For a storm of greater intensity, the numeric discharge limit will be inapplicable, although the monitoring requirements discussed below will still apply.

Discharge Monitoring Requirements

EPA has also established stormwater discharge monitoring requirements for the sites that are subject to numeric limits. These monitoring requirements are to be distinguished from long-standing inspection requirements pursuant to which a construction-related stormwater discharge permittee has been (and will continue to be) required to conduct periodic inspections of its erosion and sedimentation controls. EPA will look to each state to establish through its general permit system the details of monitoring requirements, but EPA’s notice indicates an expectation of sampling frequency no less than three (3) times per storm event.

Site Size and Timetable

EPA calls for these numeric limits and discharge monitoring requirements to apply only to construction sites at which 10 or more acres of land (contiguous or non-contiguous in a common plan of development) are disturbed at any one time. This includes linear construction projects, such as those involving most utility or transportation construction projects.

For those relatively rare instances in which a federal stormwater permit is required, EPA will include these requirements for all sites involving 20 or more disturbed acres beginning on August 2, 2011, with the size threshold dropping to 10 acres of disturbed area on February 2, 2014. The administration of the construction-related stormwater program has been delegated to the states in almost all cases, subject to EPA oversight and enforcement authority. The states are administering the program through general permits with different expiration dates. EPA is not requiring the states to revise their general permits to include these new requirements prior to the time of the normal expiration of the general permits that are presently in place. But whenever each state’s general permit is reissued, it will need to include these requirements.

Background and Implications of New Requirements

These new EPA regulations were the result of a United States District Court order that was affirmed by a United States Court of Appeals and which set a December 1, 2009 deadline for EPA to publish regulatory discharge limits and monitoring requirements (i.e., effluent limitation guidelines or ELGs) for new sources of stormwater runoff from construction sites. Stormwater monitoring at construction sites has previously been required by the states of California, Georgia, Oregon, Vermont, and Washington under their general permits, with California including a numeric discharge limit for certain types of sites.

The December 1, 2009 EPA rule also includes non-numeric effluent limitations which are essentially the same requirements as the Best Management Practices (BMPs) that are already required under the various state and federal general permits applicable to construction-related stormwater discharges, i.e., installation, inspection and maintenance of appropriate erosion and sedimentation controls, soil stabilization requirements, pollution prevention measures. However, it is anticipated that in order to meet the new numeric discharge limits, permittees may need to augment these measures with the use of sand filters, polymers, flocculants, or other measures necessary to avoid discharges into streams that exceed the new numeric limits.

The numeric limits and monitoring requirements are likely to result in increased exposure of large site construction permittees to state and EPA enforcement actions. For the past several years and on a continuing basis, EPA has targeted the large site construction industry, particularly residential subdivision developers and big-box store developers, with enforcement actions. These enforcement actions have yielded penalties in the millions of dollars and onerous decrees requiring implementation of compliance programs that go well beyond the requirements of the general permits.

Finally, although the new EPA rule and the existing general permit program apply only to the construction phase of development activity, EPA is in the process of developing stormwater effluent limitations applicable to the post-construction life of a new development. These are expected to be promulgated by November 2012. Some local and regional authorities have already established post-construction stormwater quality management requirements of which the development community should be aware.

For additional insight or assistance regarding construction and development stormwater regulatory requirements or enforcement issues, please contact any Environmental attorney on our website.