HomeMy Public PortalAboutMidwest Block and Brick 050322Metropolitan St. Louis
Sewer District
2350 Market Street
St. Louis, MO 63103
May 3, 2022
Mr. David Mudd
Midwest Block & Brick
12901 St. Charles Rock Road
Bridgeton, MO 63044
RE: Permeable Interlocking Concrete Pavement (PICP) - A Structural BMP
Dear Mr. Mudd,
The Metropolitan St. Louis Sewer District (MSD) has reviewed your application of Permeable
Interlocking Concrete Pavement (PICP). Products covered by this letter are as follows:
Turfstone EcoElite 5x10 Type 1*
Uni-Eco-Stone Mission Paver
Eco-CityLock 4x12 100mm Eco-CityLock 4x16 100mm
Eco-CityLock L-10 80mm Eco-CityLock Herringbone 80mm
Eco-Panorama Demi 80mm Eco-Cumberland Combo 80mm
* Previously marketed as "Aqua-Bric"
EcoElite L-10 Type 4*
Eco-CityLock 5x10 80mm
Eco-CityLock Demi 80mm
Eco-Venetian 80mm
Grasstone II 100mm
MSD understands that these pavers enhance surface permeability by the open space created
between the blocks and are recognized as a permeable pavement in satisfying MSD stormwater
management requirements.
MSD has determined that the PICP may be used under the following conditions:
1 Proposed uses and designs of the paving units must be in general conformance with the
information and methodologies provided previously under Kirchner Block and Brick and
by Midwest Block and Brick. Uses and designs shall also comply with the Interlocking
Concrete Pavement Institute (ICPI) and MSD's permeable pavement design and
construction guidelines.
2. Channel Protection Volume (CPv) storage may be provided in the base stone and subbase
stone beneath the PICP and bedding layer.
3. The minimum pavement section subject to vehicular traffic shall be (from top to bottom)
3 1/8 inch thick paving units, 2 -inch thick bedding stone (typically ASTM No. 8 or 9
stone), 4 -inch thick layer of base stone (ASTM No. 57 or similar size), and a layer of
subbase stone (ASTM No. 2 or similar size), all underlain by MSD type 4 filter fabric.
Metropolitan St. Louis
Sewer District
2350 Market Street
St. Louis, MO 63103
The thickness of the subbase. will vary depending on storage and anticipated traffic loads.
However, a minimum 12 -inch thick subbase will be required for all applications.
4. The post -developed curve number (CN) for the footprint of the paving units may be
reduced. Reduced CN numbers are provided below.
Soil A B C D
CN 61 61 74 80
5. The PICP system will be considered as a pervious area for the purpose of calculating
Water Quality Volume (WQv) and 5 percent impervious when calculating the differential
runoff with PI factors. However, the PICP will be considered as a 100 percent impervious
area for the purpose of calculating pipe sizes downstream and when evaluating a site's
annual post developed runoff condition.
6. PICP may be considered as a stand-alone BMP in certain design instances. Those designs
are subject to MSD review and approval.
7. Project specific design calculations and maintenance plans 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 the pavers do not satisfy MSD rules, requirements, or
construction and material specifications.
Sincerely,
zilmt
(7(4"/ -11/
Curtis Zurliene, P.E.
Civil Engineer (BMP Committee Chairman)
Engineering / Planning - Development Review
Metropolitan St. Louis Sewer District