HomeMy Public PortalAbout333052etropolitan
St. Louis Sewer
District
2350 Market Street
St. Louis, MO 63103-2555
(314) 768-6200
October 29, 2008
Mr. Glenn Byers
Stoiinwater Consultant
CONTECH Stormwater Solutions
P.O. Box 5322
Hopkins, MN 55343
RE: Contech VortSentry : 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 re -reviewed your application regarding the
VortSentry® for use as a Best Management Practice for stoiiiiwater management. Please note
that this letter replaces our previous letter of May 21, 2008. MSD is pleased to provide Highway
Use Level (HUL) and Redevelopment Use Level (RUL) approval for use of the VortSentry®. as a
stand-alone water quality BMP, subject to the following provisions.
• The VortSentry't 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 VortSentry° 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: VortSentry" Approved Model
System Model
Max Treatment Flow (cfs)
VS40
0.58
VS50
1.1
VS60
1.8
VS70
2.7
VS80
3,9
• 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.
" C o n f i n e d s p a c e e n t r y s h a l l n o t b e a r e q u i r e m e n t f o r r o u t i n e m a i n t e n a n c e . N o s p e c i a l
t o o l s o r a t t a c h m e n t s s h o u l d b e r e q u i r e d t o p r o v i d e r o u t i n e m a i n t e n a n c e w i t h a v a c u u m
p u m p i n g t r u c k .
" A l l p r o p r i e t a r y l i d s a n d c o v e r s s h o u l d b e c a p t i v e c o m p o n e n t s . T h e m i n i m u m s i z e a c c e s s
h o l e i s 3 0 i n c h e s i n d i a m e t e r .
" P r o j e c t s p e c i f i c d e s i g n c a l c u l a t i o n s a n d m a i n t e n a n c e p l a n s f u r n i s h e d b y C o n t e c h m u s t b e
i n c l u d e d w i t h i n t h e p r o j e c t '