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