2017-008 Impervious vs. Pervious Pavement Costs
Date: January 20, 2017 Report No. 2017-008
INFORMAL STAFF REPORT
TO MAYOR AND CITY COUNCIL
SUBJECT:
Pervious vs. Impervious Pavement Costs
REQUESTED ACTION:
None. Provided for information.
EXECUTIVE SUMMARY:
Council has asked staff to provide comparison of costs for impervious pavement vs. pervious pavement.
A comparison is provided herein.
DISCUSSION:
As usual, such cost comparisons are difficult to quantify and more difficult to explain. The information
presented herein was provided by a contractor who specializes in constructing, repairing and maintaining
permeable pavements in eastern TX and LA.
The most difficult comparison items to quantify for permeable pavements are the (1) reduction in costs of
stormdrainage infrastructure (inlets and stormdrainage pipe), (2) reduction in costs of stormwater facilities
(ponds) and (3) value of improvement in stormwater quality. As these factors are site specific, no
estimates can be provided that would be totally fair comparisons. However, permeable pavements will
reduce the normal additional infrastructure (and thus reduce costs) required for pervious pavements and
will improve stormwater runoff quality.
The attached chart compares initial and lifecycle costs (including related stormwater infrastructure (inlets,
stormdrains, ponds, etc.), life expectancy and annual maintenance costs) for impervious pavements
(asphalt and concrete) with porous asphalt, pervious concrete, permeable pavers and a proprietary
product, PaveDrain. The comparisons assume that related stormwater infrastructure for pervious
pavements will cost only 50% of the costs of related stormwater facilities for impervious pavements.
Since most parking lots in the Denton area are not constructed with asphalt pavement, the cost differences
between impervious concrete and pervious concrete are summarized in the table below. This table shows
the initial cost of pervious concrete is 14.3% more than impervious (conventional) concrete and has a life
cycle cost (considering related stormwater infrastructure, life expectancy, and annual maintenance costs)
of 67.5% more. Permeable pavers have essentially the same initial cost as pervious concrete and a life
cycle cost of 33.4% (1/3) more, which probably explains why most pervious parking lot installations in
the Denton area consist of permeable pavers. Again, this comparison is not an exact comparison, due to
site specific situations affecting stormwater infrastructure (inlets, stormdrains, stormwater ponds, etc.).
Nor, does the comparison attempt to quantify the value of improved stormwater runoff quality from
parking lots with the use of pervious pavements.
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Date: January 20, 2017 Report No. 2017-008
STAFF CONTACT:
John T. Davis, PE
Director of Engineering Services
940-349-7135
John.Davis@cityofdenton.com