HomeMy Public PortalAbout333048Metropolitan
St. Louis Sewer
District
2350 Market Street
St. Louis, MO 63103-2555
(314) 768-6200
July 31, 2008
Mr. Josh Dickinson
CONTECH Stormwater Solutions
6413 Lloyd Avenue
St. Louis, MO 63139
RE: Vortechs Stormwater Treatment System®: St. Louis MSD Submission
Highway Use Level (HUL) and Redevelopment Use Level (RUL) Approval within District
Dear Sir:
The Metropolitan St. Louis Sewer District (MSD) has reviewed your application regarding the Vortechs
Stormwater Treatment System® for use as a Best Management Practice for stormwater management.
MSD is pleased to provide Highway Use Level (HUL) and Redevelopment Use Level (RUL) approval for
use of the Vortechs Stormwater Treatment System® as a stand-alone water quality BMP, subject to the
following provisions.
• The Vortechs Stormwater Treatment System® is only approved for use on public highway and
roadway projects and for redevelopment sites less than 5 acres. This approval is based
compliance with requirements listed in MSD's Proprietary Water Quality Products and the
MSD's Stormwater Management Program (Jan. 2008).
• The Vortechs Stormwater Treatment System® must be sized to capture all floatable trash and free
oil, and remove 80% of total suspended solids for the OK-110 particle size distribution at the site
water quality flow -rate (WQf). Procedures for calculating WQf are provided in Appendix D.10 of
the Maryland Stormwater Design Manual (2000). Table 1 provides a list of approved models and
their respective instantaneous peak treatment WQf.
Table 1: Vortechs Stormwater Treatment System® Approved Models and Peak WQf
System Model
Max Treatment Flow (cfs)
2000
1.0
3000
1.7
4000
2.2
5000
3.1
7000
4.1
9000
5.2
11000
6.5
16000
9.3
• Devices should be configured as off-line units. In most cases the BMP will be installed without
the need to store the water quality volume (WQ,,) upstream of the unit.
• All devices shall provide a minimum sediment storage capacity of 10 ft3.
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