April 2008, Vol. 20, No.4
LID Gains Ground
Although the approach to stormwater management known as low-impact development (LID) has been around since the early 1990s, the practice has attracted significant attention in recent years as governments seek innovative methods for
protecting water quality. Recent legislative and regulatory developments involving LID are bound to increase awareness of the practice even more.
A Growing Trend
LID seeks to reduce stormwater runoff and pollutant loadings by managing runoff as close to the source as possible. Pioneered by Maryland’s Prince George’s County, LID was developed as a “complete departure from conventional stormwater management,” said Larry Coffman, widely credited as the inventor of LID. Coffman was an associate director in the Prince George’s County Department of Environmental Resources until 2004, when he left to become president of LNSB, LLLP Stormwater Services Group (Chesapeake Beach, Md.).
Rather than collecting runoff and conveying it as quickly as possible from a site, LID seeks to mimic the hydrologic functions found in a natural watershed, Coffman said. To achieve this goal, LID relies on such efforts as conserving existing natural features, minimizing imperviousness, maintaining a site’s predevelopment time of concentration, and using such practices as swales and bioretention to remove pollutants and facilitate infiltration. Other techniques common to LID include rain gardens, green roofs, and pervious paving.
“Low-impact development is becoming more institutionalized across the country,” Coffman said, particularly as increasing numbers of smaller communities seek to comply with the requirements of the stormwater phase II rule finalized by the U.S. Environmental Protection Agency (EPA) in 2003. Such communities are “looking for cost-effective, simple stormwater-management approaches and techniques,” Coffman said. “Low-impact development fits right into that.”
A recent EPA report on LID supports this conclusion. Released in January, Reducing Stormwater Costs Through Low Impact Development (LID) Strategies and Practices examines 17 case studies of developments that incorporated LID practices. Of the 12 examples that could be compared directly in terms of cost to conventional approaches to managing stormwater, only one LID project was found to cost more. In fact, the remaining 11 projects had capital costs that ranged from 15% to 80% less than their conventional counterparts, according to the report.
One reason that LID projects may cost less than traditional approaches to managing stormwater, the report notes, is that LID techniques tend to reduce the amount of materials needed for paving roads or installing curbs and gutters. Similarly, LID approaches that infiltrate or evaporate runoff “can reduce the size and cost of flood-control structures,” according to the report. Perhaps most significantly, LID practices typically can be incorporated into a yard or other developed area, obviating the need to set aside additional land for traditional management practices.
Of course, LID projects can provide other critical benefits that are harder to quantify and monetize. For example, the report notes that communities may benefit financially from LID practices that reduce the need to create or expand systems for storing or conveying runoff that otherwise would result in sewer overflows.
In the Navy
Cities and counties are not the only entities warming up to LID. The federal government is beginning to take a closer look. In fact, recent policy and legislative actions will make LID the rule for many federal facilities.
Last November, the U.S. Navy adopted a policy requiring that LID be considered as part of the design of all projects that entail stormwater management. The policy, which also applies to the U.S. Marine Corps, sets a goal of “no net increase in storm water volume and sediment or nutrient loading from major renovation and construction projects,” according to the Nov. 16 memo announcing the policy by B.J. Penn, the Navy’s assistant secretary for installations and environment. Major renovation projects are defined as those that have a stormwater component and cost more than $5 million when first approved, while major construction projects are defined as those exceeding $750,000.
Although the Navy and Marine Corps will not be required to comply with the provisions until fiscal year 2011, “all efforts shall be made to incorporate LID practices” during the interim, according to the policy. The Navy and Marine Corps also are authorized to develop a waiver process to address “those infrequent situations where LID is not appropriate given the characteristics of the site,” according to the policy.
“I commend the Navy for leaning forward and adopting LID as an integral part of its future construction and renovation projects, not only in the Chesapeake Bay, but nationwide,” said Alex Beehler, the Navy’s assistant deputy under secretary of defense for environment, safety, and occupational health, in a Dec. 5 news release. “I will be working with the other [U.S. Department of Defense] components to promote a similar approach,” he said.
The Navy’s requirements pertaining to LID may prompt even greater interest in the practice as the Defense Department implements the recommendations developed as part of the most recent round of the Base Realignment and Closure (BRAC) process, said Neil Weinstein, executive director of the Low Impact Development Center (Beltsville, Md.), a nonprofit organization dedicated to promoting sustainable stormwater management. “When they look at new construction, they’re going to have to go through this LID litmus test,” Weinstein said. “It’s setting the table” for LID, he said.
More Federal Interest
Meanwhile, a provision in the recently enacted Energy Independence and Security Act — more commonly known as the energy bill — essentially mandates the use of LID approaches to managing stormwater runoff as part of all development projects undertaken by the federal government. Sec. 438 of the law, which President George W. Bush signed on Dec. 19, stipulates that the “sponsor of any development or redevelopment project involving a Federal facility with a footprint that exceeds 5,000 square feet [465 m2] shall use site planning, design, construction, and maintenance strategies for the property to maintain or restore, to the maximum extent technically feasible, the predevelopment hydrology of the property with regard to the temperature, rate, volume, and duration of flow.”
No estimates have been made as to the number of federal facilities likely to be subject to the law’s requirement, said Dana Arnold, chief of staff for the Office of the Federal Environmental Executive. A branch of the White House Council on Environmental Quality, the Office of the Federal Environmental Executive is responsible for implementing Sec. 438. To this end, the office intends to convene an interagency work group to develop procedures for handling matters concerning the requirement, Arnold said.
Although the law’s requirement no doubt will have a positive effect on how federal facilities manage stormwater, the provision ideally would not have included a size limitation, Coffman said. Despite the fact that LID approaches can be adapted to any size development, regulated parties have been known to sidestep size requirements by dividing projects into smaller parcels that individually fit within a particular size limit, he noted.
In the Nation’s Capital
Like many older U.S. cities, Washington, D.C., faces its share of problems relating to stormwater runoff, from overburdened sewers to streams listed as impaired under Sec. 303(d) of the Clean Water Act. Already pursuing a $2 billion program to control combined sewer overflows, the district recently entered into an innovative agreement with EPA Region 3 that relies heavily on LID approaches to reduce contaminants in runoff.
The result of negotiations involving the district, EPA Region 3, and the environmental organization Earthjustice (Oakland, Calif.), the agreement is a modification to the stormwater management plan that the city must maintain as part of its existing municipal separate storm sewer system permit. The agreement includes requirements pertaining to a host of LID and other stormwater-management techniques. For example, the district must construct 17 LID projects by Aug. 9, 2009. These projects largely will entail refurbishing streets and alleyways to include best management practices that enable infiltration and remove trash, said Hamid Karimi, deputy director of the district’s Department of the Environment. Meanwhile, the city also is required to install approximately 50 rain gardens and 125 rain barrels throughout the city and disconnect 200 downspouts from the sewer system by Dec. 31, 2009.
The district also must develop a plan and schedule for converting traffic street medians, large sidewalk areas, and other paved or hardened areas into green space by the end of 2014. As it determines where to locate such measures, the city must give “highest priority” to projects that “offer the greatest storm water capture potential,” according to a summary of the agreement. The district also must promulgate new stormwater regulations that “require LID construction as a first option,” according to the summary.
Green roofs and the city’s tree canopy also figure prominently in the agreement. In fact, the district must assess all city-owned properties to determine if they are feasible candidates for green roofs. For the next 4 years, all new buildings and major renovation or rehabilitation projects constructed by the city must include green roofs where feasible. To encourage the installation of green roofs on private property, the district must establish tax credits or other incentives by mid-2009. To achieve an optimal tree canopy, the city is tasked with the goal of planting and maintaining at least 13,500 trees by 2014. The district estimates that complying with the agreement’s provisions likely will cost between $10 million and $20 million annually, Karimi said.
“We strongly believe that the totality of the program represents one of the handful — if not the single most — aggressive and comprehensive storm water management programs in the country designed to achieve pollutant reductions to the maximum extent practicable in the runoff from storm water,” said George Hawkins, director of the district’s Department of the Environment in a Nov. 27 letter to EPA Region 3.
The agreement’s provisions relating to green roofs and tree canopy cover, as well as its “clear preference” for requiring LID in the city’s stormwater ordinance, are “models” for other states and permittees to consider, said Jon Capacasa, director of EPA Region 3’s Water Protection Division. The agreement “has raised the bar, at least regionally and perhaps nationally, on what urban areas can do to solve the stormwater problem,” he said.
Making the Transition
Although it is more popular than ever, LID still has a way to go, Coffman said, noting that its “whole philosophy” has yet to be fully incorporated by state or local governments as part of their efforts to regulate stormwater management. “Few have adopted the ecological principles of LID,” he said, referring to the need to replicate the natural hydrologic regime, or water balance. Instead, many regulators advocate the use of certain LID practices, he said, while continuing to allow conventional stormwater-management approaches, even though they do not prevent the degradation of receiving waters.
This dichotomy reflects the tension between stormwater management’s original aim to control flooding and the more recent goals associated with protecting water quality. “We’re stuck in a transitional period between old stormwater management goals and objectives, which were based on controlling flows, as opposed to trying to replicate ecological processes and functions,” Coffman said. Until EPA establishes discharge standards for stormwater, he said, available technology will continue to lag behind LID’s “ultimate goal” of eliminating untoward environmental effects associated with stormwater.
— Jay Landers, WE&T