HomeMy Public PortalAboutSilva cell 11-8-13MSC
Metropolitan
St. Louis Sewer
District
2350 Market Street
St. Louis, MO 63103-2555
(314) 768-6200
November 8, 2013
Ms. Brenda Guglielmina
DeepRoot Green Infrastructure, LLC
P.O. Box 927
Decatur, GA 30031-0927
RE: Silva Cell System: St. Louis MSD Submission
Dear Ms. Guglielmina:
The Metropolitan St. Louis Sewer District (MSD) has reviewed your application regarding the
Silva Cell for use as a Best Management Practice for stormwater management. Silva Cell may
be used to supplement permeable pavement as a stand-alone water quality BMP, subject to the
following provisions:
• The Silva Cell is approved for use on new development and redevelopment sites of any
size (including roadway projects) in which permeable pavement is used.
• The Silva Cell shall be designed and applied in accordance with the details attached to
this letter. When supplemented with permeable pavement, the permeable pavement may
manage a larger upstream tributary area (up to a ratio of 4:1) as a stand-alone BMP,
regardless of the saturated hydraulic conductivity of the underlying soil.
• Channel Protection Volume (CPv) storage may be provided within the void space of the
soil media, ponding zone, and within the rock layer of the permeable pavement.
• Project specific design calculations and maintenance plans furnished by DeepRoot LLC
must be included within the project's "Stormwater Management Facilities Report"
prepared by the consulting engineer.
• The initial installation of the Silva Cell under this design criteria in the MSD shall
include the following:
1) A manufacturer's or vendor's representative must be onsite during the proprietary
BMP installation to ensure the product's installation requirements are met.
2) Shop drawings indicating elevations of flowlines, weirs, pipe inverts, etc. will be
required prior to installation.
3) The manufacturer or vendor must arrange for an as -built survey of the proprietary
BMP to be performed by a Missouri -registered Professional Land Surveyor once
the device has been installed, and prior to any testing or monitoring.
4) The manufacturer or vendor must perform quarterly inspections of the
proprietary BMP during its' first year of operation, which will include visual
inspections and quantitative analysis of the service's sediment removal
efficiency, especially as compared to its design efficiency. MSD requests to be
invited to these inspections to further enhance familiarity and understanding of
the device.
5) Formal reports shall be submitted to MSD, including as-builts and at each
quarterly inspection. The reports shall include summaries, quantitative analysis
mentioned in item 4, photographs of the structure, inlet, internal conditions of the
structure, the filters, and outfall conditions, etc. The reports shall also evaluate
the performance of the owner's adherence to the approved maintenance program,
and offer suggestions for any areas of improvement.
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,
Jason Peterein, P.E.
Principal Engineer (BMP Committee Chairman)
Engineering/Planning — Development Review
Metropolitan St. Louis Sewer District
Pc: Brenda Guglielmina — DeepRoot, LLC
File
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GEOGRID, 12" EXTENSION DOWNWARD PAST EDGE
OF SILVA CELL DECK. AFFIX TO SILVA CELL FRAME
WITH ZIP TIES
MSD TYPE 4 GEOTEXTILE FABRIC, 14' MIN EX NSION
DOWNWARD PAST EDGE OF SILVA DECK. TURN ,A D
ROOT PACKAGE AND INSTALL SOIL LIFT TO F
SURFACE ELEVATION
TREE TRUNK, SIZE VARIES
2" MULCH ABOVE TREE PIT
CURB AND STREET PER
PROJECT SPECIFICATION
TREE ROOT PACKAGE, SIZE VARIES
DEEPROOT UB 24-2 ROOT BARRIER
ANGLE OF REPOSE. VARIES PER
PROJECT SPECIFICATIONS
PLANTING SOIL, TAMPED TO MAX.
85% COMPACTION BELOW
ROOT PACKAGE
6" THICK SAND
(ASTM C-33 FINE AGGREGATE)
MSD TYPE 4 GEOTEXTILE
FABRIC ON COMPACTED
SUBGRADE
6" THICK "o GRAVEL (ASTM C-33
ND. 6 OR 67), COMPACTED TO 95%
SUBGRADE BELOW GEOTEXTLE AND
AGGREGATE BASE COURSE.
COMPACTED TO 95%
DEEPROOT UB 24-2 ROOT BARRIER
CONCRETE CURB, SIZED PER PROJECT SPECIFICATIONS,
POSITIONED OVER CELL POSTS. ATTACH TO PAVING
PERVIOUS PAVING. PER PROJECT SPECIFICATION
12" MIN. AGGREGATE BASE COURSE, PER PROJECT SPECIFICATIONS
MSD TYPE 4 GEOTEXTILE FABRIC, 18" MIN. OVERLAP PAST EXCAVATION
6" MIN PONDING SPACE BETWEEN SILVA CELL DECK AND BIORETENTION
SOIL SURFACE
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6 MIN,
PLANTING SOIL PER MSD BIORETENTION
SOIL MIX (BSM) SPECS., INSTALLED
IN 8" LIFTS (2 LIFTS PER CELL) TO
4" FROM TOP OF FRAME
SILVA CELL BASE SLOPE TO 0%1 (FLAT/NO GRADE) OVER ENTIRE
BASE SURFACE AREA
6" THICK 3/8" Q GRAVEL (ASTM C-33 NO.8), COMPACTED TO 95%
4"0 SCHEDULE 40 PVC PERFORATED PIPE, 3/8"0 HOLES, TWO SIDES,
FACING DOWN, 2" OFF BOTTOM OF EXCAVATION. CONNECT TO
OVERFLOW FOR DRAINAGE TO OFF -SITE RECEIVING AREA OR DEVICE
TYPICAL SECTION
SCALE: NTS
CLEANOUT/OBSERVATION WELL
18" MIN PAVING BASE
COURSE, PER
PROJECT SPECS.
BACKFILL, INSTALLED
IN 8" LIFTS. WITHIN 4-6"
FROM TOP OF DECKS,
COMPACTED TO 95%
SCREW CELL DECKS TO FRAMES AFTER
SNAPPING IN PLACE (TYP)
GEOGRID. 'J' 6" MIN. BELOW BACKFILL AT
BASE. OVERLAP 12" MIN. AT TOP OF CELLS.
3/16" x14" ZIP TIES, ATTACHING GEOGRID
TO SILVA CELLS AT EACH LEVEL AND AT
CELL DECK
INVERT ELEVATION SHALL NOT BE ABOVE
BOTTOM OF BSM
ANCHOR EACH SILVA CELL TO GROUND
WITH 4 - 10" SPIKE, <10MM DIA., SEE CELL
BASE FOR SPIKE HOLES. MARK UNDER -
DRAINAGE PIPE LOCATION IN BASE TO
PREVENT SPIKES FROM PUNCTURING PIPE ON
INSTALLATION
NOTES:
(1) BIORETENTION SOIL MIX (BSM) = 80% SAND. 10% FINE GROUND MULCH, 10% 'TOPSOIL", OR MIX PER MSD LANDSCAPE GUIDE FOR BMPS.
(2) SEE MSD LANDSCAPE GUIDE FOR MULCH & VEGETATION. TREES PLANTED IN BSM SHOULD BE ANCHORED.
(3) 90TH PERCENTILE (P=1.14") RAINFALL EVENT.
(4) OPTIONAL WHERE SAND CONTENT OF BSM IS HIGH (>130%).
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TREE TRUNK, SIZE VARIES
2" MULCH ABOVE TREE PIT
DEEPROOT UB 24-2 ROOT BARRIER
MSD TYPE 4 GEOTEXT1LE FABRIC, 14" MIN EXTENSION
DOWNWARD PAST EDGE OF SILVA DECK. TURN TOWARD
ROOT PACKAGE AND INSTALL SOIL LIFT TO FINAL
SURFACE ELEVATION
6" THICK SAND
(ASTM C-33
FINE AGGREGATE)
6" MIN
PLANTING SOIL PER MSD BIORETENTION SOIL MIX
(BSM) SPECS., INSTALLED IN 6" LIFTS (2 LIFTS PER
CELL) TO 4" FROM TOP OF FRAME
6" THICK 3/8"0 GRAVEL (ASTM C-33 NO.8),
COMPACTED TO 95%
6" THICK 1"0 GRAVELI (ASTM C--33
NO. 6 OR 67). COMPACTED TO 95%
(OPTIONAL) CURB STOP, PER PROJECT SPECIFICATIONS
CONCRETE CURB, SIZED PER PROJECT SPECIFICATIONS,
POSITIONED OVER CELL POSTS. ATTACH TO PAVING.
PERVIOUS PAVING, PER PROJECT SPECIFICATION
12" MIN. AGGREGATE BASE COURSE. PER PROJECT SPECS.
MSD TYPE 4 GEOTEXTILE FABRIC, 18" MIN. OVERLAP
PAST EXCAVATION
6" MIN PONDING SPACE BETWEEN SILVA CELL DECK AND
BIORETENTION SOIL SURFACE
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MSD TYPE 4 GEOTEXTILE FABRIC
ON COMPACTED SUBGRADE
PLANTING SOIL SILVA CELL BASE SLOPE TO 0% (FLAT/
NO GRADE) OVER ENTIRE BASE SURFACE
AREA
4"0 SCHEDULE 40 PVC PERFORATED PIPE,
3/8"0 HOLES, TWO SIDES, FACING DOWN.
2" OFF BOTTOM OF EXCAVATION. CONNECT
TO OVERFLOW FOR DRAINAGE TO OFF -SITE
RECEIVING AREA OR DEVICE
TYPICAL SECTION
SCALE N1S
NOTES:
(1) BIORETENTION SOIL MIX (BSM) = 80% SAND, 10% FINE GROUND MULCH, 10% "TOPSOIL", OR MIX PER MSD LANDSCAPE GUIDE FOR BMPS.
(2) SEE MSD LANDSCAPE GUIDE FOR MULCH & VEGETATION. TREES PLANTED IN BSM SHOULD BE ANCHORED.
(3) 90TH PERCENTILE (P=1.14") RAINFALL EVENT.
(4) OPTIONAL WHERE SAND CONTENT OF BSM IS HIGH (>804
PAVING BASE
COURSE, PER
PROJECT SPECS.
SCREW CELL. DECKS TO FRAMES
AFTER SNAPPING IN PLACE (TYP)
3/16" x14" ZIP TES, ATTACHING
GEOGRID TO SILVA CELLS AT EACH
LEVEL AND AT CELL DECK
BACKFILL, INSTALLED IN 8" LIFTS.
WITHIN 4-6" FROM TOP OF DECKS.
COMPACTED TO 95%
GEOGRID. V 6" MIN. BELOW
BACKFILL AT BASE. OVERLAP 12"
MIN. AT TOP OF CELLS.
ANCHOR EACH SILVA CELL TO
GROUND WITH 4 - 10" SPIKE,
<10MM DIA., SEE CELL BASE FOR
SPIKE HOLES. MARK UNDER -
DRAINAGE PIPE LOCATION IN BASE
TO PREVENT SPIKES FROM PUNCT-
URING PIPE ON INSTALLATION