construction site stormwater management building green in bowling green barry tonning tetra tech
TRANSCRIPT
Construction Site
Stormwater Management
Building Green in Bowling Green
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
Site Grading
Plan
Site Building
Plan
Site Drainage
Plan
Existing Site
Conditions
Stormwater
Pollution Preventio
n Plan
Final Site Land-
scaping Plan
Consistency between what’s in the SWPPP and BMPs installed in the
field
SWPPP Applicability, Preparation, Contents, and Process for Amending• SWPPP applies to the site AND offsite
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 as-needed basis
Basic SWPPP outline• 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)
• 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
Drainage system controls
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
• Designed & placed to pool runoff so sediment can settle out
• Installed before grading/fill work begins!
• Seeded immediately after construction
• Located in swales or low-lying areas where flows are concentrated
• Should not be placed near flowing streams
• Outlets should be made of rock or pipe
Sediment traps & basins
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
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 deviationsrequire “adequately protective” alternate practices, explainedin 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 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