HomeMy Public PortalAboutContech CDS LetterMetropolitan
St. Louis Sewer
District
2350 Market Street
St. Louis, MO 63103-2555
(314) 768-6200
January 20, 2022
Mr. Chris Allen
CONTECH Engineered Solutions, LLC
1103 Schrock Road
Suite 105
Columbus, OH 43229
RE: CONTECH CDS®: St. Louis MSD Submissions
Highway Use Level (HUL) and Redevelopment Use Level (RUL) Approval
within District
Dear Mr. Allen:
The Metropolitan St. Louis Sewer District (MSD) is pleased to provide Highway Use Level
(HUL)and Redevelopment Use Level (RUL) approval for use of the CDS® as a stand-alone
water quality BMP, subject to the following provisions.
• The CDS® is only approved for use on public highway and roadway projects and for
redevelopment sites less than 5 acres. This approval is based upon compliance with
requirements listed in MSD's Proprietary Water Quality Products and the MSD's
Stormwater Management Program (Jan. 2008).
• The CDS® 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. The 2400 micron screen
will be used.
Table 1: CDS® Approved models and Peak WQr
System Model
Max Treatment Flow (cfs)
CDS2015-4
0.6
CDS2015
0.6
CDS2020
0.9
CDS2025
1.4
CDS3020
1.7
CDS3030
2.1
CDS4030
3.9
CDS4040
4.2
• Devices should be configured as off-line units, downstream from a diversion manhole.
In most cases the BMP will be installed without the need to store the water quality
volume (WQv) upstream of the unit.
• All devices shall provide a minimum sediment storage capacity of 10 ft3
• Confined space entry shall not be a requirement for routine maintenance. No special
tools or attachments should be required to provide routine maintenance with a vacuum
pumping truck.
• All proprietary lids and covers should be captive components. The minimum size access
hole is 30 inches in diameter.
• Project specific design calculations and maintenance plans furnished by CONTECH
must be included within the project's "Stormwater Management Facilities Report"
prepared by the consulting engineer.
MSD reserves the ability to withdraw or modify this approval based on subsequent information,
including information indicating that this BMP does not satisfy MSD rules, requirements, or
construction specifications.
Sincerely,
Robert A. Miller, P.E.
Principal Engineer (BMP Committee Chairman)
Engineering/Planning
Metropolitan St. Louis Sewer District