Phase II measures impact stormwater management planning.

By Tara Beecham

Controlling water quantity and maintaining water quality are the goals of any good stormwater management plan. Yet sorting through and implementing requirements can sometimes seem overwhelming for contractors. Years ago, construction sites didn’t have to meet nearly as many stormwater management criteria as they do today, when developers often find themselves outsourcing software, installation of stormwater best management practices (BMPs), and maintenance services in an effort to protect the surrounding environment from any pollutants the runoff may carry, as well as from flooding.

The six “minimum control measures” required under the National Pollutant Discharge Elimination System (NPDES) Phase II permitting program are well known to those working in the smaller municipalities that fall under Phase II jurisdiction. The measures are public education and outreach, public participation and involvement, illicit discharge detection and elimination, construction-site runoff control, post-construction runoff control, and pollution prevention and good housekeeping. The last includes procedures for site maintenance and proper waste disposal.

Photo: CBI Engineering

Among the sediment control methods used at construction sites, silt fence remains one of the most common.

It’s the construction-site runoff control measure that has affected those in the ESC industry the most, creating new work for many and expanding awareness of the range of options for onsite sediment control. According to the EPA, the sediment runoff rates from construction sites are 10 to 20 times greater than those from agricultural lands and 1,000 to 2,000 times greater than those from forestlands, putting areas adjacent to construction sites at an increased risk of pollution. Increased sediment alone can damage lakes and streams, and various pollutants can also adhere to sediment particles.

The EPA has found that polluted stormwater runoff is a primary cause of impairment to almost 40% of surveyed US bodies of water that don’t meet water-quality standards. The Phase II requirements are in place in part to protect waterways located close to construction sites, both ongoing and completed. The EPA has determined that any construction activity that is part of what is referred to as a common plan of development or sale disturbing an acre or more must have either a permit or a waiver.

The changes these requirements have made to worksites across the country have been sweeping and enduring. Developers failing to meet the criteria set forth by NPDES face warnings or penalties.

When Phase II requirements were put into effect in 2003, companies and municipalities were forced to place an increased amount of attention on construction and post-construction stormwater management measures. While Holly Fults, a senior environmental scientist at CBI Systems in Beaumont, TX, has worked with Phase II construction general permits regulating sites less than 5 acres, she has noticed concern about stormwater management increasing among clients seeking to meet Phase II municipal permits in particular. “As the regulatory requirements increase, they are not increasing staff,” explains Fults. “I do believe they are looking for tools that will help them meet their requirements without an increase in staffs.” CBI Systems provides software, such as Construction Permit Manager and MS4 Permit Manager, to help clients comply with stormwater, erosion control, and other requirements.

Photo: Civil Design Consultants

NPDES Phase II caused engineers to incorporate post-construction measures into Santa Rosa, CA's Gordon Ranch project.

Municipalities must consider the hydraulic runoff that building concrete structures brings. While construction-site stormwater management plans are designed to prevent sediment runoff with rainwater, the runoff moves even faster along concrete than over soil, creating complications. “There are a whole host of things that can be done, but unless a city or entity is already implementing those requirements to increase hydraulic flow, then this program is something new to the entity,” says Fults. “The increased runoff is due to the concrete that is put in place of the native habitat. You have more rainfall and runoff flowing over the concrete flowing at a faster rate. They don’t have the experience, and they may not have the staff or the time.”    

Although silt fence remains the most common form of sediment control that Fults has noticed on construction sites, other methods including hay bales and vegetated buffers are also occasionally used. BMPs including sandbags can help keep water onsite, and straw wattles can help with filtration. At times, combinations of BMPs may be necessary instead of standalone practices for maximum effectiveness. “Some sites, usually 10 acres or greater, will consider a sedimentation basin,” she says, noting this will slow down the water’s flow. “When the velocity drops, you allow the particles to fall out of the retention. You have to have a site you can slope to one area. And what do you want to do when you are finished with construction and you don’t want to leave the basin in place?” A rock dam or rock berm within a ditch can be used if ditches are present on a construction site, she notes. “It works to filter some larger aggregate and slow the velocity so sediment can fall out.” Visual inspections are considered a BMP. Any spills, leaks, or discharges should be recorded by company members to prevent future problems. Stormwater pollution prevention team members will inspect any and all outside areas where there could be stormwater discharge onsite as they look for any potential pollution carried by runoff.

Some NPDES permits require sampling of a site’s discharges. The EPA and the site’s state regulatory agency must be notified by the company of these test results. If the contractor finds the site is not complying with permit conditions as a result of the testing, the EPA and state regulatory agency must also be notified. Both state regulatory agencies and the EPA can and do send inspectors to construction sites in order to determine if the site is in compliance with Phase II regulations. If a client is about to be inspected by an outside agency, CBI will help facilitate the inspection process, says Fults.

Photo: Civil Design Consultants

Adding a dry detention pond to the Gordon Ranch project design helped engineers bring it into compliance with NPDES Phase II.

At times, a site’s stormwater plan can impact its overall design. The Gordon Ranch project, a subdivision of 99 homes in Santa Rosa, CA, required considerable reworking after Phase II went into effect in order to meet the necessary stormwater planning measures.

“The project began in 2000; then we didn’t get the tentative map approved until 2003, and at that point the Phase II criteria came into play; so at that point we dropped some lots and put a dry detention pond to meet the Phase II requirements,” says Mark von Tagen, civil engineer and president of Civil Design Consultants (CDC) in Santa Rosa. When a project has to be retrofitted to meet Phase II requirements, he explained, a company could lose between 3% and 5% of the planned units.

“We have projects that are being proposed that do all the things that we know about,” says von Tagen. Managing the post-construction runoff is also a concern. “In some places we use pervious concrete. It’s project specific and site specific,” he notes. “We’ve got new projects designed around the SUSUMP [Standard Urban Stormwater Mitigation Plan] requirements. It’s almost a negotiation point with the water-quality control board as to what we are going to do.”  

Phase II requirements led the company to consider post-construction BMPs, as did the SUSUMP conditions, which call for source control, treatment control, and minimizing channel-forming discharge. Source control can include adding signs to catch basins to discourage illegal dumping of hazardous substances; treatment control includes the basins themselves; and reducing discharge ensures the “peak [runoff] for the post-project will not be any greater than the peak pre-project,” he notes.

Photo: Environmental Logistics of Colorado

Erosion blankets are just one aspect of Colorado Springs' Stetson Ridge project's stormwater management plan.

Post-construction measures posed the need for retrofitting at the Gordon Ranch project. “We were meeting to the full extent the Phase I requirements, which didn’t require post-construction measures,” says von Tagen. “The difficult part of this is to get the people who live in the subdivision to make sure their impacts are being mitigated.”

Often a client approaches CDC and says his or her company needs to meet SUSUMP requirements. A report is prepared to meet the requirements of the respective water-quality control board. While CDC had used a standard erosion control plan, the company is considerably more concerned with stormwater management since Phase II went into effect.

 “There are several types of bioretention ponds, and there are vegetated swales,” says von Tagen, noting that he designs these for specific sites. “We’d all like to find the black box where the water goes into and comes out clean. The black box doesn’t exist.”

The company relies on Santa Rosa–based KriStar Enterprises, which provides inlet filtration products, for many BMPs. “The filters have the ability to address some of the criteria,” says von Tagen. “They have provided good products for a long, long time.”

Photo: Winzler and Kelly

In Rohnert Park, CA, EC blankets and hay help protect seeds and encourage vegetation growth in a drainage pipe area.

At times, state and local water-quality regulations can be more stringent that those set by the EPA. Although an area’s water control board might impose fines after an inspection if necessary, von Tagen hasn’t seen citizens’ groups lobbying for more stringent enforcement of the water-quality regulations.

“I have seen an outcry from local public agencies that say it’s an unfunded mandate from the state,” he says, adding that he works with the state and individual groups to make changes. “Part of my job is to get the state and the local agency to work together to be able to build projects.”

Environmental Logistics of Colorado (ELC), a Denver-based company that provides maintenance and site inspection work for clients, also has found clients very interested in meeting stormwater treatment goals. The company reviews site stormwater management plans to see if they are optimal for a site. Additionally, ELC assists with installation and implementation of the stormwater plan, along with maintenance of the system.

ELC recently worked on the Stetson Ridge project in Colorado Springs, CO. The Stetson Ridge site includes check dams, erosion blankets, silt fencing, vehicle tracking control pads, concrete washouts, and filter socks within its stormwater management plan. “We used a filter sock as perimeter control,” explains Jennifer Mirowski, president of ELC. There is another site adjacent to that, Eastview.” The Eastview site uses the same BMPs, says Mirowski, in addition to vegetated buffer strips as part of its stormwater management plan.

“We do a lot of inlet protection with compost socks,” says Mirowski. “We do that for 90% of our homebuilders.”

Mirowski stresses the importance of looking before design begins at the water sources that could impact the site. Planning for post-construction runoff is then determined by complying with the EPA and the state-based requirements.

“Basically, you want to keep everything onsite,” says Mirowski. “They will do whatever it takes to keep it onsite.”

She has noticed homebuilders are aware of stormwater management and how the regulations are being enforced, adding that the department of transportation in her state was recently fined $2 million for non-compliance issues.

Mirowski has also noticed an increasing number of compliance inspections in her area. “This year the EPA has been out in the field checking,” she says.

ELC works on design with an engineering firm, Paradigm Engineering, headquartered in Lewisville, TX, but all other work is completed in-house. Municipalities frequently seek the help of an outside contractor as they face stormwater management requirements. Cristina Goulart, an environmental scientist at Winzler and Kelly Consulting Engineers in Santa Rosa, CA, helps smaller cities meet Phase II stormwater management criteria.

“The cities that we work with already had been doing stormwater management to some degree,” says Goulart. “Basically, we first looked at what they are already doing and improved upon that.”

Several Winzler and Kelly clients already had stormwater management practices in place, but they approached the issue in terms of flood prevention, she explains. As a result of Phase II, they need to incorporate pollution prevention into their designs as well. And controlling post-construction runoff has become a much bigger priority in a project’s design.

“The cities are still struggling with that a little bit. It’s a new requirement,” says Goulart, referring to the Sonoma County region. “The local cities that we have been helping have been looking to Santa Rosa. They just completed a guidebook for post-construction design.”

Other cities are now looking at the example set by Santa Rosa as well. “Rohnert Park has already adopted it,” says Goulart, adding that during work on a sewer project for the city, erosion control blankets and hay surrounded the drainage pipe area, protecting seeds in a bare ground setting so vegetation growth would hold within the soil. “I think that’s how it’s probably going to happen.”

Teamwork is taking stormwater planning into the future in the area. The Russian River Watershed Association is coming together with local cities and looking at the region as a watershed, explains Goulart. The groups hope to pool resources and determine whether some of the pollution-prevention activities and habitat restoration can be done collectively.

 “I’m excited about it,” says Goulart, noting this could be a potentially valuable pollution-prevention strategy. Landscape planning that includes water conservation can also underscore an increased need for managing runoff. For example, at Matanzas Creek Winery, lavender gardens were established to form low-water-use landscaping that reduces the need for irrigation.

Some companies are using Internet-based tools to help them meet compliance measures. Michele Hincks of Enviance, a company based in Carlsbad, CA, that provides environmental compliance software, explains that in the past, a company would purchase software from a vendor with a code that remained behind that company’s firewall. This would require the person to upgrade the software when this vendor makes changes or upgrades.

“Enviance has one common set of servers. We host everything. Everybody has a password, and when they plug in their password on our Web site, then their system shows up,” she explains. “Everyone has the same baseline technology. When we do an upgrade, we shut down the system Friday night and then by Sunday we are up and running, all new data transferred in.”

Fults also helps clients implement the use of her company’s software to meet compliance regulations. “It keeps your data centralized. It’s a Windows approach to writing the stormwater plans,” she says. “When you can log all of your data about a site such as dates of inspection in one place, it’s easier to provide the big picture for your client.” When designing stormwater pollution prevention plans, which are always site specific, the EPA recommends considering area precipitation levels, soil types, the site’s slope, and any hazards stormwater controls such as retention ponds may pose to the safety of children located near the site. BMPs used vary with the size, geographic type, and budget of the site.

Low-impact development (LID) techniques are growing in popularity as companies aim to keep post-construction runoff onsite. Methods such as porous pavement, rain gardens, and swales are often used.

“We have seen an increase in LID techniques within the last few years,” notes Mirowski, adding that some of the techniques she has seen used include the expansion of green spaces and organic BMPs such as compost filter socks. “The compost can then be added as soil amendments and help establish vegetation.”

Fults has also noticed an increasing number of municipal clients seeking to incorporate LID techniques as part of post-construction stormwater management plans. “They are more open to giving the option to developers to allow them to consider LID BMPs,” she says. “The porous pavement is climate and soil specific. Here in our area it’s just not feasible; we have a heavy clay soil,” making it difficult for runoff to infiltrate.

There are other LID techniques she has seen clients in the area use, however: “Bioretention, filter strips, and vegetated swales are the most common.”

Bioretention makes full use of soils and plants to eliminate pollutants from stormwater runoff. It’s a BMP worth considering for median strips and onsite swales, according to the EPA, and should be installed upland from inlets. Grasses will slow the flow of the runoff while a sand bed will filter particulates. Using a bioretention system can reduce a site’s stormwater management system’s overall cost.

Permeable pavers or porous pavement can eliminate standing water onsite and facilitate the removal of pollutants. Rain gardens that contain water onsite, maintaining a natural hydrology; green roofs that reduce pollution and control nitrogen levels in runoff; and rain barrels, which contain runoff from rooftops for later irrigation use, are also common LID techniques incorporated into post-construction design. Vegetative BMPs often increase a site’s aesthetics as well.

Goulart explains the efforts of the City of Cotati, CA, to pull green elements into regional landscaping. “They really want to have a demonstration garden that would have climate-appropriate landscaping,” she says. “We’ve got green lawns. During the summer months, approximately half of the water use is for yards.” The garden has received local support, and a landscaper who has experience with native plants is working on the project.
Similar to LID principles, Winzler and Kelly works with clients to keep stormwater runoff onsite or treat it as necessary prior to leaving the site, explains Goulart. This process primarily begins before, not during, construction with the grading of the site itself.

 “If it’s designed with stormwater issues in mind, you can have a grassy swale,” she says.“One local winery has a quarter-mile-long grassy swale. All the runoff from the winery gets directed through that swale. It would be a lot harder to put that in afterward. That’s really the direction that we want to move in.”    

As additional water-quality measures and innovative LID techniques are considered early in project cycles, retrofitting a site to handle runoff will become increasingly infrequent.

Based in Morgantown, PA, writer Tara Beecham is a frequent contributor to Erosion Control.

EC - July/August 2006