RFI - Attachment F - Engineering Report

REVIEW


    1. Review of StormFilter®Treatment System, Sampling and Methodology
The StormFilter® system described in the report (Contech 2012) is made up of an eight (8)
cartridge StormFilter® preceded by a detention tank designed to capture 75% of the runoff
volume from the 1.0 inch (25.4 mm) event. The catchment to the system consists of a 1.08
acre (0.437 ha) carpark with an equivalent impervious area of 0.73 acres (0.297 ha)
representative of a catchment that is 68% impervious.

The layout provides for detention of the runoff with a controlled discharge to the StormFilter®
treatment system at a flow rate determined by the hydraulic capacity of eight (8) StormFilter®
cartridges. Each cartridge was filled with an activated alumina coated perlite media
(PhosphoSorb).

The layout of this treatment system allows the catchment hydrology to be modified based on
the hydraulics of the tank cartridges and media rather than the runoff characteristics of the
catchment. This system provides a generic layout suitable for applications where there are
major constraints on the available site area for treatment options. It could be expected that
the alumina coating on the perlite media would enhance the adsorption of pollutants onto the
exterior of the perlite media, while the perlite itself has a demonstrated ability to absorb
pollutants (Siber A et al, 2011)

Influent and effluent samples were collected using twelve (12), 1 litre sample bottles.
Collection of flow proportional samples commenced once the flow rate exceeded 5 g(US)pm
(0.32 L/s). The sample strainers intakes and flow measurement equipment were secured to
the invert of the influent and effluent pipes, which biases the samples towards the larger
fraction of the suspended solids. Collection and testing of the samples was carried out by
Pace and TestAmerica independent of Contech and oversight of the project was provided by
Ryan Winston, MS, extension Associate in the Department of Biological and Agricultural
Engineering at North Carolina State University.

Rinsate blank and replicate samples were collected, which is consistent with the sampling
guidelines detailed in NWQMS (2000) and demonstrates scientific rigour within the sampling
methodology as well as a good understanding of the vagaries of sampling rainfall/runoff
events.

    2. Sampling “chain of custody”
Personnel from Pace and TestAmerica collected the samples and delivered them to the
laboratory for testing. No record of the use of “chain of custody” procedures for the samples
is referred to in the Porject Evaluation, submitted for this peer review. However,
correspondence with Contech Engineered Solutions has identified that “chain of custody”
procedures, similar to those outlined in Sections 4 and 5 (NWQMS, 2000) and Section 6
(EPASA, 2007), were employed as part of the sampling Project Plan. Further, Pace and
TestAmerica are accredited laboratories in accordance with the National Environmental
Laboratory Accreditation Conference (NELAC) and all samples were tested in accordance
with their nationally approved testing protocols (John Pedrick pers com).




HES – StormFilter® System Peer Review                                                      Page 2