Building Green in Bowling Green
Construction Site
Stormwater Management
Barry Tonning
Tetra Tech
State and local rules require:
• Local and state permit
coverage
• SWPPP available for
review
• BMPs in the field that
match the SWPPP
• Contractors’ weekly
inspection forms
available for review
Minimizing the active construction area
Consistency between what’s in the
SWPPP and BMPs installed in the field
Site
Grading
Plan
Site
Drainage
Plan
Existing
Site
Conditions
Site
Building
Plan
Final Site
Landscaping
Plan
Stormwater
Pollution
Prevention
Plan
SWPPP Applicability, Preparation,
Contents, and Process for Amending
• SWPPP applies to the site AND offsite
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borrow/disposal areas
SWPPP is prepared BEFORE filing the NOI and
beginning work
SWPPP describes site, pollutants at site, plan for
controlling pollutant discharges, construction
procedure, & responsible parties
SWPPP is amended by site personnel or project
engineer as construction proceeds on an asneeded basis
Basic SWPPP outline
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Site description & map
Description of receiving waters
Description of construction project
Identification of pollutants, sources,
and any non-stormwater discharges
Erosion & sediment controls
Controls for other pollutants
Procedures for inspections, BMP
maintenance, and recordkeeping
Certification & signatures
Building, stabilizing, and preserving the
drainage system (ditches, traps, ponds)
Drainage system controls
• Inlets for storm drains and channels
– Pond up the runoff to settle & filter it
– Use rock berms, rock bags, or other items
• Storm drain & channel outlets
– Protect areas receiving discharge flows from erosion
caused by flow velocities
– Use rock or turf reinforcement mats; seed heavily
• Ditches – convey water without eroding
• Traps – pond and settle out muddy runoff
Good application of silt
fence and rock bags for
inlet protection – Lots of
options available
Other inlet protection approaches
Outlet Protection
Drainage ditch liner materials
• Steep or high flow channels (> 20%)
– Use concrete or riprap
• Moderately steep channels (~ 10%)
– Use riprap or turf mats & seeding
• Slightly sloping channels (~5%)
– Use turf mats or blankets & seeding
• Mostly flat channels (~2%)
– Use seeding with blankets
Seed ditches immediately after construction
Triple the seeding rate
Sediment traps & basins
• Designed & placed to
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pool runoff so sediment
can settle out
Installed before
grading/fill work begins!
Seeded immediately after
construction
Located in swales or lowlying areas where flows
are concentrated
Should not be placed
near flowing streams
Outlets should be made
of rock or pipe
Rock filter as sediment trap
Good siting
&
installation
of sediment
traps
Protecting riser during
construction!
* Wrap with filter fabric
* Use rock inlet dam
* Pile #57s around pipe
Buffer zone requirements
• 25 ft undisturbed buffer between disturbed
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areas and bankfull elevation of high quality
waters / impaired waters
50 buffer required between sediment-impaired
waters with no TMDL and disturbed areas
Dredge/fill areas,
stream crossings,
or other deviations
require “adequately
protective” alternate
practices, explained
in SWPPP
Buffer Zone
• Edge of Receiving Water is defined as bankfull
elevation of a water of the Commonwealth
Slope stabilization
Slope protection basics
• Seed and mulch immediately after grading
• Divert upland runoff with berms or channels
• Tread-track or terrace highly erodible soils
• Install sediment barriers at toe of slope and
at correct spacing on long slopes
• Use blankets, mats, or mulch on steep slopes
• Control runoff from upland areas with drain
pipes or lined downdrain channels
Mass grading tips
• Install all downgradient silt fences, traps,
basins before clearing & grubbing
• Use grubbed-out debris as sediment
barriers / berms downhill from your work
• Use soil stockpiles as sediment berms /
traps that intercept concentrated/sheet
flow
• Seed and mulch/blanket/mat your ditches
and slopes as soon as you build them
Blankets and mats
(rolled erosion control products)
• Excellent for slope and
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channel protection
Use blankets for slopes
flatter than 3:1 and
channels flatter than 20:1
Use mats for slopes greater
than 3:1 and channels
steeper than 20:1
KY TC requires blankets in
all channels & slopes > 4:1
Wishful thinking . . .
Stabilization requirements
• Temporary stabilization required on
portions of the site where construction
activities have temporarily ceased shall be
initiated within 14 days
• Final stabilization also required within 14
days after permanently ceasing work
• Final stabilization required if work is
suspended for more than 180 days
Homebuilder lot BMP compliance
Fiber roll installation
Good housekeeping & pollution prevention
Good housekeeping
• Mud tracking on roadways
• Fuel, oil, paint, hazardous waste mgmt
• Concrete washout sites
• Trash & debris management
• Sewage management
• Dust control (if needed)
Waste management
Provide
convenient,
well-maintained
toilet facilities
Establish proper
building material
handling and
storage areas
Building
materials with
runoff potential
should be
stored indoors
or under cover
Designate concrete washout areas
Or wash out material in formed-up
areas ready for the next pour
Establish proper equipment/vehicle
fueling and maintenance practices
• Your on-site fueling and
maintenance area should
have a spill kit
• Conduct vehicle fueling
and maintenance activities
in areas away from ditches
• Conduct maintenance on
vehicles and equipment
off-site if possible
Develop a spill prevention and
response plan
• Note the locations of
chemical storage areas,
storm drains, ditches,
and surface waters
• Specify how to notify
appropriate authorities
• Describe the procedures
for spill cleanup
• Identify personnel
responsible for
implementing the plan
The Good, The Bad, and the Ugly
• The Good – stabilized exit pads, initial silt
fence installation, initial inlet protection
• The Bad – temporary seeding/mulching,
silt fence maintenance, inlet maintenance,
waste and materials management
• The Ugly – ditch and channel protection,
some homebuilder lots
Fair construction entrance; poor silt fence
Good fence, needs seed/mulch
Good inlet protection
Good stabilization on pipe job
Well vegetated sediment basin, with poorly
vegetated inactive area in foreground
Poor vegetation and no sign of active grading
Unstabilized slope
Lot with poor vegetation and poor silt fencing
Lack of inlet
maintenance
and sediment
management
Poor stabilization & drainage management
Eroding, unstabilized drainage swale
Poor site stabilization, drainage system, and
sediment trap construction & maintenance
Overflowing concrete washout
Vacant inactive site with poorly
installed silt fence and poor vegetation
Poor soil stabilization, shaky silt fence,
ineffective inlet protection
Torn and frayed
Poor site management