Monday, October 27, 2008

Pavement that Detains and Infiltrates Runoff

Like infiltration trenches, permeable interlocking concrete pavements (PICPs) are highly effective in providing infiltration, detention and treatment of storm water pollution. The base can be designed to filter, treat and slowly release water into a storm sewer or water course while providing a walking and driving surface. PICPs limit the amount of impervious cover flowing into storm drains working at capacity, or when sites have limited space for detention ponds.

The U.S. Environmental Protection Agency (EPA) and several state agencies consider PICPs an infiltration Best Management Practice (BMP). An increasing number of cities, counties and states are incorporating them into land development and runoff standards, low-impact development guidelines and design manuals on stormwater control. With proper design, material selection, construction and routine maintenance, PICP is a sustainable low-impact BMP used by landscape architects, architects, engineers, developers and public agencies.

PICPs have been widely used across Europe, especially Germany since the early 1990s. The projects demonstrate runoff reduction and improved water quality in a range of climates, soils, hydrological and regulatory environments.

Concrete Pavers Contribute to the LEED Green Building Rating System

Originally developed for the U.S. Department of Energy, Leadership in Energy and Environmental Design (LEED) is growing in use by design professionals in response to federal, state, and local government agencies, and by private developers. LEED uses a point rating system to recognize sustainable site and building design. Complying with the rating system is voluntary and it aims to improve environmental and economic performance of buildings and sites. Developed by consensus with the participation of many organizations, the rating system and certification program (based on providing evidence of compliance to the rating system) is administered by the U.S. Green Building Council. A complete description and downloads can be found on the Internet at www.usgbc.org/LEED.

Runoff Reduction
Concrete pavers and permeable interlocking concrete pavers can earn points or "credits" in the LEED rating system. Credits are earned under several categories of use including stormwater management, local/regional materials, and exterior design to reduce heat islands. For stormwater management, Credit 6.1 (1 point) can be earned for building sites where the existing impervious area is greater than 50%. Permeable interlocking concrete pavement can meet this requirement. In some urbanized areas with this extent of impervious cover, permeable interlocking concrete pavement may be more cost-effective than a separate detention facility due to space contraints. The LEED requirement is that runoff rate and quantity be reduced by at least 25%. Permeable interlocking concrete pavements can reduce runoff to zero for the most frequent storms.

Cleaning Up Runoff
Credit 6.2 provides 1 point for treatment systems designed to remove 80% of the average annual post development total suspended solids (TSS), and 40% of the average annual post development total phosphorus (TP). The ability of permeable interlocking concrete pavements to reduce these pollutants is typically greater than these percentages according to references in the Interlocking Concrete Pavement Institute's manual, Permeable Interlocking Concrete Pavements—Selection, Design, Construction, Maintenance. The ICPI manual references studies on infiltration trenches (similar to permeable pavement bases) and porous pavements with reductions in TSS as high as 95% and TP as much as 70%.

Local Materials
Another source of credit is designated as Credit 5 (1 to 2 points), local regional materials: specify a minimum of 20% of building materials that are manufactured regionally within a radius of 800 km (500 miles). An additional point is earned if 50% of the regionally manufactured materials are extracted, harvested or recovered within this same radius. Most interlocking concrete pavers and permeable pavers will be manufactured within this distance from the project site.

Walking on the Sun
Perhaps the most intriguing Credit is 7.1 (1 point), landscape and exterior design to reduce heat islands. An option for meeting this requirement is to use lightcolored/high albedo materials with a reflectance of at least 0.3 for 30% of the sites non-roof impervious surfaces, i.e., pavements. Concrete paving units can be manufactured in practically any color, so they can be tailored to register an albedo of at least 0.3.

Albedo is the ratio of outbound or reflected solar radiation to inbound radiation. It is measured with a pyronometer, a device that is mounted on an arm that of Horizontal and Low-Sloped Surfaces in the Field. The pyronometer is made by The Eppley Laboratory Inc., 12 Sheffield Avenue, Newport, Rhode Island 02840 tel: 401-847-1020, www.eppleylab.com. According to President, Tom Kirk, the device can be rented for US$1500 for two months or purchased with the tripod and readout for $3750. He noted that long term measurements should be done with two pyronometers rather than one, to better understand and compare diurnal changes in the radiation flux of pavements. He also noted that there are certain winter months of the year that the equipment can't be used due to a low angle of the sun. This will depend on the latitude at which the measurements are taken.

According to a year 2000 study by Lawrence Berkeley National Laboratories, new asphalt exhibited an albedo of 0.04 and five year-old pavements 0.12, substantially lower the 0.3 recommended in the LEED rating system. In their experiments, they found that an increase in albedo of about 0.1 produces a change in pavement temperature of about -4º ±1º C (-7º ±2º F) when there is little wind. Increasing wind speed lowers the surface temperature and diminishes the influence of the change in albedo. Fresh concrete has an albedo of about 0.35 and higher reflectance can be achieved with light colored or white cement and light colored aggregates. While the study didn't examine concrete pavers, they likely can easily meet this recommendation in the LEED rating system if manufactured with natural or light colored finishes.

In conclusion, LEED seeks materials with local material use, high reflectance or albedo, plus runoff and pollution reduction potentials. Interlocking and permeable concrete pavers can contribute credits to sites and buildings evaluated under the LEED rating and certification.

Sunday, October 26, 2008

What is Permeable Interlocking Concrete Pavement?


Permeable interlocking concrete pavement (PICP) is comprised of a layer of concrete pavers separated by joints filled with small stones.
Water enters joints between solid concrete pavers and flows through an "open-graded" base, i.e. crushed stone layers with no small or fine particles. The void spaces among the crushed stones store water and infiltrate it back into the soil subgrade. The stones in the joints provide 100% surface permeability and the base filters stormwater and reduces pollutants.


Sustainability and PICP

Permeable Interlocking Concrete Pavements (PICPs) are eligible for LEED® credits under the U.S. and Canadian Green Building Councils (USGBC and CaGBC) guidelines. PICP can meet the LEED® credit requirements under Sustainable Sites. These requirements limit runoff and water pollution by managing stormwater. The pavements can reduce runoff-generating impervious cover and decrease the rate and quantity of runoff. PICP meets these credits through the filtering action of the base that reduces total suspended solids and phosphorous in runoff, as well as other pollutants.


PICP can also meet the sustainable sites requirement to reduce urban heat islands (thermal difference between urban and rural areas), minimize impacts on microclimates and in wildlife habitats. This is accomplished through increased albedo (a measure of the solar energy reflected from a surface) or use of a pavement system with less than 50% imperviousness. PICP has substantially higher reflectivity than conventional asphalt pavement and can meet the requirement for less than 50% imperviousness.


PICP typically meets the requirements for Conservation of Material and Resources, Recycled Content under the USGBC LEED for new construction where at least 20% of the building products should be manufactured within a radius of 500 miles (800 km) of the project. Most paving units are locally manufactured and delivered to projects within 500 miles (800 km). To find the closest manufacturer or distributor visit the ICPI Find A Member section. For additional information on U.S. or Canadian LEED credits visit www.usgbc.org or www.cagbc.org.





NCMA SCORES VICTORY FOR SUSTAINABLE DESIGN

Landmark Legislation directs DOD to incorporate “principles of sustainable design” and “life-cycle cost-effective practices” in military construction.


(Herndon, VA) October 21, 2008 – President Bush has signed into law the Department of Defense (DOD) authorization bill for fiscal year 2009, legislation which funds the nation’s military programs. The bill includes a major provision that addresses one of NCMA’s top legislative priorities. That particular provision requires the Secretary of Defense to incorporate principles of sustainable design and life-cycle cost-effective practices as an element in all military construction projects submitted to Congress for approval. All projects submitted by DOD elements—including the U.S. Army, Navy, Marine Corps, and Air Force—will have to take into account these criteria.

By enacting this provision, Congress is validating through legislation the arguments long articulated by NCMA and the concrete masonry industry that the DOD should be utilizing construction materials that are more sustainable and cost-effective over the life cycle of the construction project. These new requirements will likely require a significant paradigm shift
on the part of the DOD in the way building materials are selected. While some military service branches have continued to favor the use of durable building materials—which provide maximum long-term sustainability and lower maintenance costs—other branches have sacrificed long-term cost-effectiveness and performance in the interest of achieving short-term
objectives.

“NCMA has continued to take the lead in working with members of the U.S. Congress to ensure that design priorities for military construction are properly realigned,” according to NCMA President Bob Thomas. “This legislation is of particular importance to NCMA members, as well as other segments of the masonry industry and members of the North American Concrete Alliance (NACA). We look forward to working with our industry partners in supporting the military service branches in the months and years ahead to fully implement these provisions.”

“From the beginning of our dialogue with Congress going back to last year, the House Armed Services Committee members and senior staff expressed a willingness to work with NCMA to address our ongoing concerns regarding the choice of building materials used to house our troops,” declared Don Foster, Chairman of NCMA’s Government Affairs Committee.

“Our legislative effort focused on the 2009 DOD authorization bill as the appropriate legislative vehicle in which to seek to incorporate the life-cycle language.”

"This statutory change is aimed at beginning the shift away from the use of less durable, less sustainable building materials in military construction projects,” continued Thomas. “Greater opportunities are expected in these projects for the use of materials such as concrete masonry, which not only have a lower life-cycle cost than other construction materials, but also provide the enhanced security and fire protection that our military personnel deserve, while accomplishing the objectives of energy conservation and sustainability required for all new government construction. This legislation will spur growth for our member companies, provide jobs within those communities hosting military bases, and enhance our industry’s role as
responsible stewards of our environment.”

About the National Concrete Masonry Association (NCMA)

The National Concrete Masonry Association (NCMA) is the global trade association representing the concrete masonry and hardscape industry. The Association is involved in a broad range of technical, research, education, marketing, certification, communications, and government relations activities. NCMA is an association of producers of concrete masonry and hardscape products, and suppliers of products and services related to the industry. NCMA offers a variety of technical services and design aids through publications, computer programs, slide presentations, and technical training.

Please visit

www.ncma.org for additional information.