HomeMy Public PortalAbout333064Metropolitan
St. Louis Sewer
District
2350 Market Street
St. Louis, MO 63103-2555
(314) 768-6200
January 27, 2010
Mr. John S. MacKinnon, P.E.
Hydro International
94 Hutchins Drive
Portland, Maine 04102
RE: Hydro International Up -Flo® Filter (with Downstream Defender as Pretreatment)
Redevelopment Use Level (RUL) + Provisional Use Level (PUL) Approval within District
Dear Sir:
The Metropolitan St. Louis Sewer District (MSD) has reviewed your application regarding the Up -Flo
Filter for use as a Best Management Practice for stormwater management. MSD is pleased to provide
Redevelopment Use Level (RUL) + Provisional Use Level (PUL) approval for use of the Up-F1o1)
Filter (with Downstream Defender as Pretreatment) as a stand-alone water quality BMP, subject to the
following provisions.
• The Up -Flo® Filter is approved for use on redevelopment sites of any size. This approval is
based on compliance with requirements listed in MSD's Proprietary Water Quality Products
and the MSD's Stormwater Management Program (Rev. Jan. 2009). Proprietary devices
should be treated as a supplementary (rather than a primary) means of meeting small MS 4
requirements.
• Proposed uses and designs of the device must be in general conformance with the information
and methodologies provided in Hydro International's application dated December 16, 2009.
• The use of buried filters shall be avoided on residential type projects.
• The Up -Flo® Filter must be sized to capture all floatable trash and free oil, and remove 80% of
the total suspended solids for the site Water Quality Volume (WQ,). Procedures for calculating
WQ,, are provided in Volume I of the Maryland Stormwater Design Manual (2000). All units
shall be installed with adequate storage to treat 75% of the WQ,.,.
• The peak inflow is limited to 20 gpm (0.045 cfs) for each 1.1 ft2 Hydro -Filter -Sand (HFS)
filter module (18.2 gpm/ft2) and an operating head of 20 inches above the filter. Each module
shall be designed for an annual sediment removal of less than 190 lbs. The minimum size
orifice between the WQ„ storage vessel and filter vault is 1.5 inches (with orifice protection).
• Up-FIo" Filter systems must provide a minimum of 2.8 ft3 of sediment storage volume for
each filter module. The sediment storage should be provided in the sump below the filter
modules.
• The device must be configured so that the outlet module is closed off from the outfall (i.e., the
bypass weir shall not be used). All units including pretreatment, should be configured in an
off-line layout.
• Adequate pretreatment shall be provided in all site designs in this case this will likely include
Downstream Defender unit. No reduction in the number of filter modules shall be made for
the installation of pretreatment. The Downstream Defender shall be sized to remove 50% of
the TSS (OK-110 PSD) at the water quality flowrate (WQf).
• All units shall include at least one (1) drain down filter. Replacement of the draindown filter is
required anytime inspection reveals that the water level within the filter structure is not equal
with the base of the filter modules within 36 hours of the design storm.
• All proprietary lids and covers should be captive components. At least one "oversized" access
shall be provided on the filter vault and storage chamber (each). The Neenah MH R-1741-F1,
or equivalent, MSD approved cover is required over the storage chamber. The Neenah MH R-
1741-D cover, or equivalent, MSD approved cover is required over the filter vault.
• Project specific design calculations and maintenance plans furnished by Hydro International
must be included within the project's "Stormwater Management Facilities Report" prepared by
the consulting engineer. The devices maintenance plan shall be consistent with the plans
presented in Hydro International's Up -Flo® Filter applications.
• In addition to testing and reports to be provided as part of NJCAT field-testing, Hydro
International will provide local field-testing and observations in accordance with the
November 2009 QAPP for Quality Assurance Testing at the Brentwood Target T-1102 for the
Up -Flo® Filter and Downstream Defender.
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,
ro,c,LA T
Michael T. Buechter, P.E.
Principal Engineer (BMP Committee Chairman)
Engineering/Design
Metropolitan St. Louis Sewer District