HomeMy Public PortalAbout398872BMP DRAINAGE AREA MAP PREPARATION INSTRUCTIONS
In addition to the drainage area map provided for the storm sewer design, also provide a
BMP drainage area map in the plan set and stormwater management facilities report that
meets the following requirements:
• Show drainage areas that drain to each BMP, and also show credited areas. Only
show “big picture” drainage areas tributary to each BMP/Credit…for this
particular map do not show the drainage areas as broken out into sub-areas.
• Show the following on the BMP DRAINAGE AREA MAP:
a. Disturbed area limits
b. The tributary BMP drainage areas, labeled by area name
c. North arrow
d. Scale
e. Contours
f. Area indicators
g. Site improvements (surfaces, buildings, roads)
h. All utilized BMPs and credits
i. BMP/credit summary table (see attached example)
j. Property lines
k. Lot numbers
l. Addresses
• Include the following notes on the BMP DRAINAGE AREA MAP:
ANY FUTURE LAND DISTURBANCE, INCREASE IN IMPERVIOUS AREA,
AND/OR CHANGE IN RUNOFF CONDITIONS ON THIS SITE MAY
REQUIRE ADDITIONAL STORM WATER MANAGEMENT PER MSD
REGULATIONS IN PLACE AT THAT TIME (INCLUDING TOTAL LAND
DISTURBANCE AND/OR IMPERVIOUSNESS ADDED ON THIS PLAN).
LAND DISTURBANCE AREA (THIS PROJECT) = ________ACRES
LAND DISTURBANCE AREA (CUMULATIVE) = ________ACRES
EXAMPLE BMP/STORMWATER CREDIT SUMMARY TABLE
(COMMERICAL DEVELOPMENT)
Area
Land
Disturbance
BMP
Drainage Structural BMP Stormwater Credit WQv Storage WQv Storage
Name Area (Ac) Area (Ac) Required (Cu. Ft.) Provided (Cu. Ft.)
A 2.8 3 Bioretention - 2000 2100
B 3.9 4 Bioretention - 2300 2450
C 1.5 1.5 Permeable Pavement - 1900 2100
D 2 2 - Sheet Flow to Buffers - -
Total 10.2 10.5
EXAMPLE BMP/STORMWATER CREDIT SUMMARY TABLE
(ROADWAY RETROFIT)
Area
Land
Disturbance
BMP
Drainage Structural BMP WQv Storage WQv Storage WQf WQf
Name Area (Ac) Area (Ac) Required (ft3.) Provided (ft3) Required (cfs) Provided (cfs)
A 1.7 1.7 Permeable
Pavement 2000 2100 -- --
B 2.5 3.0 Hydrodynamic
Separator -- -- 3.7 4.2
Total 4.2 4.7