Saturday, November 08, 2008

Benefits of Pervious Concrete Pavement & Permeable Pavers

ABSTRACT: In Fiscal Year 2007/08, the City expended $21,727.15 for pervious concrete and permeable pavers as part of the “Forest Study Implementation Project.” The total revised budgeted amount for the “Forest Study Implementation Project” was $50,000.00. Photos of the installed pervious concrete pavement and permeable pavers are shown. Information about pervious concrete pavement and permeable pavers is presented. COMMENTS are made with regard to the dual purpose benefit of pervious concrete pavement and permeable pavers; the cumulative surface area covered by the pervious concrete pavement and permeable pavers; the monetary amount expended relative to the total budgeted amount for the “Forest Study Implementation Project;” and a future plan to implement fully the recommendations of the "Forest Study." REFERENCES are presented.

Pervious Concrete Pavement
Along Lincoln St., east side, south of Ocean Av.

Close-Up of Pervious Concrete Pavement
Lincoln St. & Ocean Av., S.E. Corner

Permeable Pavers
E/s Lincoln St., between 5th Av. & 6th Av., mid-block next to "landmark" Eucalyptus Tree

Close-Up of Permeable Pavers
E/s Lincoln St., between 5th Av. & 6th Av.

Pervious concrete pavement

Pervious concrete pavement is a unique cement-based product whose porous structure permits a free passage of water through the pavement into the soil without compromising the pavement’s durability or integrity. This concrete also goes by other names including “permeable” and “enhanced porosity.”

As a generic material, all have been recognized by the U.S. Environmental Protection Agency as a storm water pollution prevention (SWPP) Best Management Practice device.
Pervious Concrete is a zero-slump, no-fines, open-graded material consisting of Portland cement, coarse aggregate, admixtures, and water. The combination of these materials will produce a product that will allow water to pass through it. The void structure is normally between 18-to 25%. Compressive strength designs are in the range of 3000 to 4000 psi.

What Are Permeable Pavers?
Permeable Pavers are a paving alternative to more traditional types of hardscape flooring materials, where water is allowed to filtrate through the surface to the underlying soils. Traditional pavers do not allow much water to infiltrate particularly if they are mortared in place, water would normally hit the surface and then flow down to the nearest drainage channel, and become stormwater runoff.
If we use Permeable Pavers we will be preserving the quality of our water, and also increasing the quantity of good quality water. Stormwater brings with it pollutants, chemicals, fertilizers, sediment and oils, destroying the quality of water flowing into the catchment areas. Permeable pavers permit rain water to be absorbed by the ground underneath, while still managing to provide a stable enough surface for vehicles.

The Advantages of Using Permeable Pavers
Increase in water quality
Increase in quantity of quality water
Reduce installation costs of drainage system
Reduces stormwater runoff
Reduces flooding
Reduces erosion caused by flooding
Preserves our stream beds and river banks

Environmental Benefits
Permeable Pavers can help preserve our environment and the most precious resource of all, water. We can’t live without water, and what permeable pavers do is help protect the quality of our water supplies. They reduce the amount of stormwater runoff entering our natural waterways and carrying with it contaminants and pollutants. So, the water is allowed to naturally drain into the surface through the voids in the permeable pavers. This promotes the infiltration of rainwater and also helps to recharge the groundwater.

Another environmental benefit is that applying Permeable Pavers means less stormwater runoff, which means that our streams and river beds are less likely to flood as often. This also means that there will be a reduction in the rate of the erosion of river banks and stream beds.

Economical Benefits
There is a lot of money saved when using Permeable Pavers, particularly in the installation and construction phases. Contractors and builders will save money on drainage systems and retention systems. Installing permeable pavers means that you are installing a self drainage system at the same time. You can also save on expensive compliance regulations. Not only will the contractors and builders save but so will their customers.

So, there is money saved on actual parts and systems, but there is also money saved on time taken to complete installation. Because a Permeable paving system kills two birds with one stone, installation time is significantly reduced.

Pervious concrete pavement and permeable pavers are “a storm water pollution prevention (SWPP) Best Management Practice device” and beneficial for trees in the commercial district, hence a dual purpose benefit. However, the expenditure of nearly one half the total budget for the "Forest Study Implementation Project" in fiscal year 2007/08 expended on pervious concrete pavement and permeable pavers covering approximately 200 linear feet or less than one block face cumulatively is questioned as to whether that is the best expenditure of finite, limited funds dedicated to the implementation of the Forest Study.

Going forward, given the demonstrated environmental benefits to pervious concrete pavement and permeable pavers, it would be wise for the City to consider the installation of permeable pavement surfaces throughout the commercial district, installed in phases over time, and a vastly increased budget overall for the "Forest Study Implementation Project" to include other items directly related to trees ex. the purchase, planting, watering and nurturing of trees, the hiring of a certified arborist to complete a comprehensive inventory of public and private trees, et cetera.

May 2008 Check Register
(Includes checks dated 4/25-4/29/08)

115329 4/29/08 JOE BRUNO CONSTRUCTION $ 2,820.00

June 2008 Check Register
115605 6/10/08 S&J CARRERA CONSTRUCTION $ 18,907.15

2008/09 THROUGH 2010/11

Funds are budgeted to provide for planning and construction of major capital improvements. The capital projects, submitted by departmental staff and their respective commissions or boards, are selected through an in-depth evaluation prioritization process and then reviewed and approved by the City’s Planning Commission

Revised 07/08
$ 50,000 01-89639 Forest Study Implementation

Revised 08/09
01-89639 Forest Study Implementation $ 20,000


Anonymous said...

Those pavers in the pictures don't appear to be of the permeable type, but just conventional pavers which are non-pervious. Regarding the costs, when compared side by side to the total cost of other BMPs, permeable pavers are often less expensive.

VillageinForest said...

Quite right. Thank you for the correction. Please see edited post above with photo of permeable pavers.

Anonymous said...

This is a perfect example of the city's priorities. Where is the Forest and Beach Commission? With the city's urban forest in severe decline because of an excess of tree removals and inadequate tree plantings, how can the city expend half its forest study budget for permeable sidewalks for a small area when the trees are dying and being removed and no trees are being planted?
Just recently visitors staying with us noticed the difference in the number of trees and feeling of tree canopy and cover from their last visit 5 years ago, and they were astonished with the fewer numbers of trees in Carmel-by-the-Sea and the lack of tree age diversity in the forest.