Post-Construction Runoff Control
Reducing long-term pollutant loads
The EPA stated in the NPDES Phase II final rule, “Post-construction stormwater management in areas undergoing new development or redevelopment is necessary because runoff from these areas has been shown to significantly affect receiving waterbodies. Many studies indicate that prior planning and design for the minimization of pollutants in post-construction stormwater discharges is the most cost-effective approach to stormwater quality management.
“There are generally two forms of substantial impacts of post-construction runoff. The first is caused by an increase in the type and quantity of pollutants in stormwater runoff. As runoff flows over areas altered by development, it picks up harmful sediment and chemicals such as oil and grease, pesticides, heavy metals, and nutrients [e.g., nitrogen and phosphorus]. These pollutants often become suspended in runoff and are carried to receiving waters, such as lakes, ponds, and streams. Once deposited, these pollutants can enter the food chain through small aquatic life, eventually entering the tissues of fish and humans.
“The second kind of post-construction runoff impact occurs by increasing the quantity of water delivered to the waterbody during storms. Increased impervious surfaces [e.g., parking lots, driveways, and rooftops] interrupt the natural cycle of gradual percolation of water through vegetation and soil. Instead, water is collected from surfaces such as asphalt and concrete and routed to drainage systems where large volumes of runoff quickly flow to the nearest receiving water. The effects of this process include streambank scouring and downstream flooding, which often lead to a loss of aquatic life and damage to property.”
To minimize this impact, EPA has directed each small MS4 covered under a Phase II permit to develop, implement, and enforce a program to reduce pollutants from post-construction runoff. This applies to new development and redevelopment projects involving land disturbance of 1 acre or more.
To satisfy this requirement, each MS4 is required to do the following:
- Develop and implement strategies including a combination of structural and non-structural best management practices (BMPs);
- Have an ordinance or other regulatory mechanism requiring the implementation of post-construction runoff controls to the extent allowable under state, tribal, or local law;
- Ensure adequate long-term operation and maintenance of controls; and
- Determine the appropriate best management practices and measurable goals for this minimum control measure.
The EPA Phase II Final Rule offers suggestions regarding BMPs that may be used to implement these requirements. Structural BMPs might include:
- Stormwater retention/detention systems to control stormwater by gathering runoff in wet ponds, dry basins, or multichamber catch basins and slowly releasing it to receiving waters or drainage systems. These practices can be designed to both control stormwater volume and settle out particulates for pollution removal.
- Infiltration BMPs, such as infiltration basins/trenches, dry wells and porous pavement. These facilitate the percolation of runoff through the soil to ground water, and thereby result in reduced stormwater runoff quantity and reduced mobilization of pollutants.
- Vegetative BMPs can assist in removing pollutants and also facilitate the percolation of runoff, maintaining natural site hydrology, promoting healthier habitats, and increasing aesthetic appeal. Examples include grassy swales, filter strips, artificial wetlands and rain gardens.
Non-structural BMPs may involve:
- Planning procedures, such as local master plans and zoning ordinances intended to promote improved water quality. An example would be to guide the growth of a community away from sensitive areas to areas that can support it without compromising water quality.
- Site-based BMPs, including buffer strip and riparian zone preservation, minimization of disturbance and imperviousness, and maximization of open space.
St. Tammany Parish, LA
Located about 30 minutes from New Orleans, on the north side of Lake Pontchartrain, St. Tammany Parish was once a rural area. By 2000, the parish (what most other states refer to as a county) had grown to a population of 191,000. By 2004, it was estimated that approximately 212,000 residents lived in the area.
Then Hurricane Katrina hit, making its final landfall over eastern St. Tammany Parish in August 2005.
“There was so much damage, it looked like somebody dropped a bomb,” says Sabrina Schenk, watershed coordinator for St. Tammany Parish. “I lost 127 trees in my yard. It wasn’t just New Orleans—if you lived anywhere near Lake Pontchartrain, there was severe damage. I did without power for six weeks, and I had three trees in my house.”
Despite the ravaged area, the population of the parish swelled as people left areas even harder hit. Census figures aren’t yet available, but it is estimated that St. Tammany Parish is now home to approximately 264,000 residents.
Schenk is also the acting MS4 administrator for the unincorporated part of the parish, as well as an NPDES certified stormwater inspector and erosion control inspector. She is the only stormwater coordinator that St. Tammany Parish has known.
The parish’s initial Phase II permit was issued in December 2002, with the second becoming effective in December 2007. “About 10 years before Phase II was required, this was still a very small rural community, a farm community, and it is now an urban community,” says Schenk. “When you make those kind of changes, it is difficult. At that time, it was very hands-off: ‘Let me do my farming, my agricultural work the way I do it, and leave me alone.’ It has since urbanized; there have been so many changes in that time frame. I can pretty well assure you that there wasn’t much in effect before we were required to do so. I’m not saying there wasn’t anything, but I would say very little.”
Schenk has a strong background in the construction and post-construction runoff control measures. “I used to work in Environmental Services with their permit program in 2002 and 2003, but since 2004, I have been the construction runoff coordinator,” she says. “When I came in, there really wasn’t anything; there had never been a stormwater coordinator. I’m the first one we’ve ever had. There was nothing back in ’04. When I came in, our builders went down kicking and screaming. They didn’t want to install silt fencing, they didn’t want to install BMPs, they didn’t want to do any of it. They had to be convinced that it was the law and it was required, and they were going to have to do it.
“We’ve been taking baby steps with them. The initial ordinance was very brief and very basic: Keep your dirt on your site; you figure out the method. If it’s doing the job, we won’t really say a lot. The inspection process was also very basic—we only had two inspections, and we didn’t do any unscheduled inspections under the original ordinance. The only unscheduled inspections were based on complaints.
“Now that we’re ramping up for our second Phase II permit, we’re actually in the process of revising our stormwater ordinances. Under the second permit, we’re doing things like unscheduled inspections, not necessarily complaint-driven.”
At present, commercial properties of less than 2 acres need to show a 10% reduction in stormwater runoff for a 25-year storm. For properties of 2 to 5 acres, a 15% reduction is required for a 25-year storm, and above 5 acres, the requirement is a 25% reduction for a 100-year storm.
To meet these goals, she says, “The BMPs used can be detention ponds, linear ponds, or underground storage. We don’t tell them what kind, we just tell them what numbers they need to meet. They have to submit engineering reports. Their engineers do the inspections, then submit reports to us weekly during construction. After construction is complete, they will be required to submit quarterly reports.”
She adds that the parish will occasionally do spot checks to ensure compliance. When she previously worked in a similar capacity for the town of Longview, TX, she had a rotation of about 300 sites, all of which were evaluated within a two-year period. “Everybody got checked at least once in that two-year time frame,” she says. “I’m looking to do something like that here.”
Regarding funding, she notes that the general fund provides some tax revenue, with additional money coming from grant funding, permit fees, and inspection fees. Schenk very much wants her programs to be largely self-funded through various permit and inspection fees, rather than trying to squeeze more from the parish general fund.
“I don’t see it being funded any other way,” she says. “People here are strapped; they’re going to say no if we put it to a vote. So it’s going to have to be funded through the permit fees and the inspection fees. It’s going to have to fund itself.”
One way she envisions this being done is through a draft ordinance that is presently in the works. “In our draft ordinance, the post-runoff control includes a BMP maintenance permit,” she explains. “It is retroactive in that current subdivisions and current commercial developments will be surveyed. Those that are already complete will be required to get a maintenance permit, so that they will be taken into inventory. They will also have to have a maintenance permit, and they also will be required to be inspected, just like the newer ones, so they won’t fall through the cracks.
“We’ve got hundreds upon hundreds of existing permanent structures that are already installed, and they would otherwise not fall under this new ordinance. In order for that not to happen, over a three-year process, all of those are going to be surveyed, and one by one permitted under the new ordinance. So they will be inspected, there will be a permit fee so we can afford this process, and there will be an inspection fee. That initial inspection will take place by our staff so that we know what’s there. Then it will be turned over to them, and will be required to be inspected by their engineering firm. We do consider this very important. We want to know what’s out there and we want to know what shape it’s in.”
Schenk mentions that although St. Tammany Parish runs its own stormwater program, it also coordinates with nearby entities. “We get a lot of assistance from neighboring communities, non-profits, regulatory authorities in the form of monthly St. Tammany Watershed Task Force meetings, and quarterly Louisiana Urban Stormwater Coalition meetings. We meet with the city of Mandeville; the city of Covington; our state authority, the Louisiana Department of Environmental Quality; the Louisiana Department of Health and Hospitals (the entity that permits the installation of the individual sewer systems); and the Lake Pontchartrain Basin Foundation. All these people get together monthly, and we talk about different things that are going on. That includes public education, pamphlets that need to be put out, programs that need to be run, things that we can coordinate together.”
To date, there has not been an EPA audit in St. Tammany Parish. “We are not one of the hot ones on their list to be audited,” says Schenk. “They’ve been here, they’ve visited us, they know our program well. They know we’re functioning well; they’re not real concerned about our program, so we’re kind of on the back burner.”
Asked to describe the success of her programs, she proudly states, “Other MS4s look to St. Tammany Parish for guidance and assistance. We are considered a cutting-edge program in the state of Louisiana. Implementation of the six minimum control measures—I renamed them the “Sacred Six”—has been quite successful.”
Looking back, however, she does note one problem getting the initial program off the ground. “With our first construction ordinance, I’m not going to say we didn’t do proper public notice, because you have to. It goes out in the newspaper, but just because it goes out in the newspaper and has all the proper public notice, doesn’t mean that the proper people are reading it and getting notified. When it went out, I will say our building community felt like they were not consulted properly. They felt that they could have been better notified, and there was a lot of ill will.
“This time, with the draft revisions of the ordinance, we have worked very closely with the building community, the development community. In fact, we’ve been having meetings with them for two years. I’ve been meeting not only with them, but also with the League of Women Voters, and Tammany Together, which is a nonprofit group. It’s a community organization that looks at everything from environmental to community issues. We’re trying to get everybody on board with the revisions in the ordinance.
“We don’t want to fight anybody this time. This time we want everybody informed. If I have any advice for trying to put an ordinance forward, you can’t necessarily make everybody happy, but at least make them feel that they were vested in it, they were in the loop. Don’t just put it in the newspaper and announce it. Hold community meetings, let them have a voice, let them be a part of it well in advance. It will make a difference, even if they don’t agree with everything you put in it. They will at least feel as if they have a say.”
Situated about 60 miles northeast of Denver, and within 30 miles of the foothills of the Rocky Mountains, Greeley, CO, is a community of some 89,000 residents, according to the latest estimate (2006) from the US Census Bureau.
Theresa Kohls is the stormwater quality administrator for the city, and has been involved with the stormwater program since its inception. In addition, she represents Greeley on the Permit Compliance Committee for the Colorado Department of Health and Environment.
Kohls notes that the initial Phase II permit for the city was issued in 2003, with the second permit coming in 2008. Greeley’s third permit term is scheduled to begin in March 2013.
“The city of Greeley’s construction program is operating under several regulatory mechanisms,” says Kohls, “and these mechanisms allow the city to require BMPs and enables sanctions to ensure compliance.” She notes that a number of ordinances relating to post-construction runoff control were in place even before the enactment of Phase II regulations.
|Photo: City of Portland
Rain gardens and other vegetative BMPs can fit in small spaces.
For example, in 1996, a grading and erosion control ordinance was added to the Greeley municipal code and was later revised in 2003. Land development regulations were enacted in 1998, with revisions coming in 2002. In addition, subdivision regulations became part of the municipal code in 1998, and were further revised in 2003. The city’s stormwater management program was originally enacted in 1995, and revised in both 2001 and 2008. There are also individual development agreements, which require appropriate BMPs as well as long-term maintenance. Further, there is a land development code requiring that site plans submitted for review and construction in the city must also include drainage facilities that are compliant with a number of ordinances. Some of these ordinances date back to 1997, with multiple revisions since.
At present, Kohls explains, “Post-construction runoff controls are typically detention ponds with permanent water-quality features, like water-quality plates. During construction, permanent BMPs and infrastructure are inspected for proper installation, and after construction the stormwater facilities are inspected and permanent post-construction BMPs are inspected by the city for conformance with city requirements and specifications prior to the issuance of the first building permit. Until final stabilization of the project is obtained, regular inspections of the BMPs are conducted under our construction program, then inspections of structural BMPs continue on a routine basis.”
Enforcement actions, when required, may include verbal warning to property owner, written notice of violation to property owner, a site meeting, chargeback for work completed by the city or a contractor hired by the city, or a court summons.
To fund its stormwater program, Greeley utilizes a stormwater utility that is billed monthly on customers’ utility bills.
Kohls keeps careful tabs on the division of labor in her department. “These minimum control measures are managed through the Stormwater Quality section of the Stormwater Management Division,” she says, “and my group has about 9% of the total Stormwater Management Division budget. There are three full time employees in the water-quality group, two technicians who perform most of the day-to-day inspections and investigations involved with these minimum control measures. In my position as stormwater quality administrator, I have overall responsibility for our state-issued stormwater permit.”
She adds that 13% of her water-quality budget is devoted to the minimum control measure of post-construction runoff control, with 17% of her staff time dedicated
toward this measure.
Kohls describes her program as “somewhat successful” and notes that post-construction inspections are continuing to increase yearly. She says that some early planning, prior to the implementation of Phase II, helped a great deal. “The forethought of the public works director in establishing ordinances before the city had to obtain its permit, and the structure of the department, has been a big asset in meeting the requirements of the minimum measures.” To date, there has not been an EPA audit, but Kohls expects one to take place within the next couple of years.
Looking ahead, she says the city’s goal is to “continue to follow and enforce based on our stormwater management plan and the individual minimum control measure program plans. We also want to revise the ordinances so that we can issue administrative hearing notices instead of taking offenders to municipal court.”
Asked if the stormwater department might have done anything differently in hindsight, Kohls echoed the thoughts of a number of other communities. “In my opinion, the department could have done a better job of reaching out to the citizens concerning the utility and explaining why it was needed,” she says. “We still have citizens who do not understand the utility and what the money is used for.”
Steve Goldberg writes on issues related to erosion control and the environment.