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Permeable Paver Costs

Initial expenses for alternative paving materials may be more than if conventional methods are used.  However, the use of permeable pavers can often eliminate the requirement for underground storm drain pipes and conventional stormwater systems.  Cost savings due to decreased investments in reservoirs, storm sewer extensions, and the repair and maintenance of storm drain systems should be considered. In general, the multifunctionality of permeable pavers saves money.

In large jobs, such as shopping parking lots, builders can use permeable pavers as a stormwater management tool, making the job far less expensive than the construction of, for example, a paved surface and a stormwater pond.  When correctly accounted for, permeable pavers serve both as a necessary structure and part of the stormwater system.  If ordinances are written to give builders credit for the stormwater management capabilities of permeable pavers, the job becomes far less expensive than the standard parking lot and retention basin combination.1  As Bill James, University of Guelph engineering professor states, a water-treatment system can be built right into our roads, providing a way to filter polluted water running off paved surfaces.2 Land costs are saved, and municipalities gain the added benefits of flood prevention and ground water recharge.1

Although the exact amount varies widely, builders can expect an increase in installation costs for permeable pavers relative to asphalt.  However, when all factors are considered (i.e., decreases in stormwater conveyance and other stormwater management installations), the use of permeable pavers can be cost effective.3 As a specific example, the use of porous asphalt has been stated to cost about 10 percent more than the use of an equivalent amount of non-porous asphalt.  But since the porous asphalt is also part of the drainage system, when the total cost of site development is added up, these permeable systems are said to be able to produce savings of more than 30 percent in favorable sites.4

Some on-the-ground success stories include that of Westfarms Mall in Connecticut where a turf parking lot was installed.  The mall's general manager reports that she found the cost comparison between grass paving and asphalt to be even at about five years, with a decided turf advantage after that.  Most importantly, though, besides reducing stormwater runoff and improving water quality, the four-acre turf parking lot also met the permeable greenspace requirements that were necessary for mall expansion.5 In addition, the city of Kinston, North Carolina, recently installed over 8,500 square feet of turfstone and grass paver parking.  With subgrade materials having similar costs for any type of pavement, the in-place cost for 2" asphalt was estimated at $6,500, while material costs for the permeable pavers came to $6,200 - creating a project comparable or even reduced in costs.6

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Cost Guides

Data or studies that compare construction, maintenance, and life cycle costs for stormwater management systems are limited. The wide range of site conditions and design requirements also makes it difficult to determine the life cycle cost benefits. It is recommended that each potential application be evaluated on a site-by-site basis. However, a range of cost estimates for the basic installation of permeable paver materials is given in the table below for comparison purposes.7 The wide range of costs for the paver systems should be noted.

Paver System Cost Per Square Foot (Installed)
Asphalt $0.50 to $1.00
Porous Concrete $2.00 to $6.50
Grass / gravel pavers $1.50 to $5.75
Interlocking Concrete Paving Blocks $5.00 to $10.00*
*dependent on depth of base and site accessibility, per conversation with Maryland Unilock® representative (2002)

Users should also keep in mind that a more accurate price comparison would involve the costs of the full stormwater management paving system.  For example, a grass / gravel paver and porous concrete representative stated that when impervious paving costs for drains, reinforced concrete pipes, catch basins, outfalls and stormwater connects are included, an asphalt or conventional concrete stormwater management paving system costs between $9.50 and $11.50 per square foot, compared to a permeable paving stormwater management system at $4.50 to $6.50 a square foot. The savings are considered to be even greater when pervious paving systems are calculated for their stormwater storage; if designed properly, they can eliminate retention pond requirements.8

1 Krueger, G., 2000: Pervious paving offers one solution to city's flooding problem. Savannah Morning News, web posted February 12, 2000. Search the News archives for the Local section at  http://www.savannahnow.com/.

2 Canadian Water and Wastewater Association, 2001: Porous pavement cleans up water run-off: 'Green' roads would improve the environment. Bulletin, 15 (5) June. Accessible at http://www.cwwa.ca/bul-old.htm.

3 North Carolina State University Cooperative Extension Continuing Education Course on Permeable Pavements developed by Bill Hunt in the Department of Biological & Agricultural Engineering.  See http://courses.ncsu.edu/classes-a/bae/cont_ed/pavement_course/index.htm for more information.

4 Ferguson, B.K., 1996: Preventing the problems of urban runoff. Washington Water RESOURCE, the quarterly report of the Center for Urban Water Resources Management, 7(4) Fall.  Accessible at http://depts.washington.edu/cuwrm/ under Subscriptions.

5 White, P., 1996: A whole lot of turf - permeable paving permits mall expansion in Connecticut. Turf Magazine, February.  Accessible at Invisible Structures, Inc. Grasspave2 web site http://www.invisiblestructures.com/GP2/whole_lotof_turf.htm.

6 For more information on the project contact Scott Stevens, P.E., Kinston City Engineer at scott.stevens@ci.kinston.nc.us.

7 Numbers compiled from:
     Peterson, C., 2001: Pervious Paving Alternatives. http://www.petrusutr.com/paving_paper.htm.

     EPA, 2000: Low Impact Development (LID) - A Literature Review. EPA-841-B-00-005, Office of Water, Washington, D.C.

     Booth, D.B., J. Leavitt and K. Peterson, 1997: The University of Washington Permeable Pavement Demonstration Project – Background and First-Year Field Results. Accessible at http://depts.washington.edu/cuwrm/ under Research.

8 Chere Peterson of PETRUS UTR, Inc., 2002, personal communication

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