RFI - Attachment F - Engineering Report

February 29, 2012

John H. Pedrick
Contech Construction Products, Inc.
11835 NE Glenn Widing Drive
Portland, OR 97220

John,

This letter provides a review of my involvement in the evaluation of the Stormfilter Stormwater
Treatment System at Mitchell Community College in Mooresville, North Carolina. I was approached by
Contech in October of 2010 to serve as a Technical Advisor (TA) for the project. As a TA, I provided
support and guidance for the stormwater monitoring and evaluation of the Stormfilter from start to
finish. This included review of monitoring methods and procedures as well as a site visit to observe and
verify field monitoring setups.

I am well qualified to serve as technical advisor for this project. I earned my M.S. degree in 2009 at
North Carolina State University by completing a stormwater monitoring project. I have been intensively
involved in field monitoring of more than 30 stormwater BMPs in North Carolina, including bioretention,
permeable pavement, cisterns, filter strips, swales, and innovative wet ponds. Apart from field data
collection, I have been involved in the production of 10 peer‐reviewed journal articles and numerous
final reports. Therefore, I have a solid background in statistics and stormwater data analysis.

From the start, I have reviewed and approved all reports produced on the data collected on the
Mooresville Stormfilter. This included the Quality Assurance Project Plan (QAPP) in October 2010, the
first quarterly report in May 2011, and the second quarterly report in August 2011. In short, the
methods that have been used to monitor the Stormfilter are state‐of‐the‐science, and provide an
excellent indication of how the product performed over the eight month evaluation period. The final
report (February 2012) for the removal of solid pollutants provides NCDENR with the requisite
monitoring data to show that the Stormfilter removed 85% of TSS during the 10 storm events that were
sampled. A second report will be produced on the other analytes that were sampled, including
nutrients and heavy metals.

Should you have any questions, please do not hesitate to contact me.

Thank you,




Ryan J. Winston, M.S., E.I.