The Permeable Pavement Technical Standard 1008 has been updated with minor revisions regarding TSS load reduction. The document provides technical specifications for the design, modeling, construction, implementation, and maintenance of permeable pavement for purposes of compliance with storm water post-construction performance standards in Ch. NR 151, Wis. Adm. Code.
The revised version of the standard is posted on the DNR website at: http://dnr.wi.gov/topic/stormwater/standards/const_standards.html
A summary of the revision is as follows:
- The TSS load reduction value in Table 2 has been changed from 55 to 65 percent. Under Criteria V.L.3.c., a pollution reduction credit of 55 percent was given for the portion of the average annual runoff volume that passes through the pavement surface and discharges through the underdrain. This value was selected in 2014 based on a literature review, and reflected a conservative value representing the low end of the reported spectrum. Since then, WDNR, WDOT, USGS, and companies representing the permeable pavement industry began a study in Madison, WI designed to address problems identified with studies in the literature review. Data from 28 runoff events have since been evaluated and the final value of 65 percent was selected. The value for the TP Removal Credit in Table 2 remains at 35%.