HomeMy WebLinkAbout262.60BIORETENTION SOIL MIX, COMPOST,
AND MULCH SPECIFICATIONS
STD. PLAN - 262.60
PUBLIC WORKS
DEPARTMENT
APPROVED:
DATEMartin Pastucha
Public Works Administrator
UNLESS OTHERWISE NOTED, DRAWING IS NOT TO SCALE (NTS)
BIORETENTION SOIL MIX
BIORETENTION SOIL MIX (BSM) SHALL BE A WELL-BLENDED HOMOGENEOUS MIXTURE OF 60 TO 65 PERCENT BY VOLUME MINERAL
AGGREGATE FOR BIORETENTION SOIL AND 35 TO 40 PERCENT BY VOLUME COMPOST AS DETAILED IN THE TABLES BELOW.
TABLE: MINERAL AGGREGATE GRADATION
SIEVE SIZE PERCENT PASSING
3/8-INCH 100 PERCENT
U.S. NO. 4 95 TO 100 PERCENT
U.S. NO. 10 75 TO 90 PERCENT
U.S. NO. 40 25 TO 40 PERCENT
U.S. NO. 100 4 TO 10 PERCENT
U.S. NO. 200 2 TO 4 PERCENT
COMPOST
COMPOST MUST ORIGINATE A MINIMUM 65 PERCENT BY VOLUME FROM
RECYCLED PLANT WASTE COMPRISED OF YARD DEBRIS, CROP RESIDUES,
AND BULKING AGENTS, AND MEET THE DEFINITION OF "COMPOSTED
MATERIAL" IN WAC 173-350-100. COMPOST SHALL HAVE A MOISTURE CONTENT
THAT HAS NO VISIBLE FREE WATER OR DUST PRODUCED WHEN HANDLING
THE MATERIAL. COMPOST SHALL HAVE AN ORGANIC MATTER CONTENT OF 40
PERCENT TO 65 PERCENT BY DRY WEIGHT, A CARBON TO NITROGEN RATIO
BELOW 25:1, AND A pH BETWEEN 6.0 AND 8.0
TABLE: COMPOST GRADATION
SIEVE SIZE MIN. PERCENT PASSING
2-INCH 100 PERCENT
1-INCH 99 PERCENT
5/8-INCH 90 PERCENT
1/4-INCH 75 PERCENT
ABORIST WOOD CHIP MULCH
ARBORIST WOOD CHIP MULCH SHALL BE COARSE GROUND WOOD
CHIPS (APPROXIMATELY 1/2" TO 6" ALONG THE LONGEST DIMENSION)
DERIVED FROM THE MECHANICAL GRINDING OR SHREDDING OF THE
ABOVE-GROUND PORTIONS OF TREES. IT MAY CONTAIN WOOD, WOOD
FIBER, BARK, BRANCHES, AND LEAVES, BUT MAY NOT CONTAIN
WEEDS, WEED SEEDS, OR VISIBLE AMOUNTS OF SOIL.
TABLE: ARBORIST WOOD CHIP MULCH GRADATION
SIEVE SIZE PERCENT PASSING
6-INCH 100 PERCENT
2-INCH 95 TO 100 PERCENT
1-INCH 70 TO 100 PERCENT
5/8-INCH 0 TO 50 PERCENT
U.S. NO. 4 0 TO 30 PERCENT
MINERAL AGGREGATE FOR BIORETENTION SOIL
MINERAL AGGREGATE FOR BIORETENTION SOIL MUST BE FREE OF WOOD,
WASTE, COATING, OR ANY OTHER DELETERIOUS MATERIAL, AND ALL
AGGREGATE PASSING THE NO. 200 SIEVE SIZE MUST BE NON-PLASTIC.
MINERAL AGGREGATE MUST BE ANALYZED BY AN ACCREDITED LAB USING
THE SIEVE SIZES NOTED IN THE TABLE TO THE LEFT, AND MUST MEET THE
REQUIRED GRADATIONS.
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8/13/2020 | 8:48 AM PDT