CEPSCI Construction Site BMPs and Implementation 2 — Questions and Answers
Question 1: What is the primary purpose of inlet protection (e.g., a filter sock or gravel bag around a storm drain inlet)?
- To increase the capacity of the storm drain
- To prevent sediment-laden runoff from entering the storm drain system (Correct answer)
- To mark the inlet location for the contractor
- To aerate the water before it enters the drain
Correct answer: To prevent sediment-laden runoff from entering the storm drain system
Inlet protection devices filter sediment out of runoff before it enters the storm drain, preventing sediment from being conveyed off-site through the stormwater system.
Question 2: A compost sock (bio-roll) used for erosion control is most appropriately installed:
- At the top of slopes to divert water
- Along the contour of slopes to intercept sheet flow and filter sediment (Correct answer)
- Inside storm drain pipes
- Vertically on steep embankments
Correct answer: Along the contour of slopes to intercept sheet flow and filter sediment
Compost socks installed along slope contours intercept and slow sheet flow, filtering sediment and allowing infiltration while the compost material biodegrades over time.
Question 3: What is a 'diversion' BMP and what is its primary function?
- A device that filters sediment from runoff
- A constructed channel or berm that intercepts and redirects runoff to a safe outlet or treatment area (Correct answer)
- A chemical treatment for stormwater
- A type of inlet protection device
Correct answer: A constructed channel or berm that intercepts and redirects runoff to a safe outlet or treatment area
Diversions (channels, berms, or ridges) intercept upslope runoff and redirect it away from active disturbed areas or toward a sediment control practice for treatment.
Question 4: Which temporary stabilization method is most appropriate for areas that will be reactivated within 2 weeks?
- Permanent seeding and fertilization
- Temporary mulching with straw or hydraulic mulch (Correct answer)
- Concrete paving
- Installation of riprap armoring
Correct answer: Temporary mulching with straw or hydraulic mulch
Temporary mulching protects bare soil from rainfall impact and erosion without establishing permanent vegetation, making it easy to re-disturb the area when work resumes.
Question 5: A turbidity curtain (silt curtain) is used to:
- Control erosion on steep slopes
- Contain sediment in open water bodies such as rivers, lakes, or bays during in-water work (Correct answer)
- Filter inlet runoff on land
- Divert stormwater around a work site
Correct answer: Contain sediment in open water bodies such as rivers, lakes, or bays during in-water work
Turbidity curtains are floating barriers deployed in water bodies to contain sediment plumes generated during in-water construction activities such as dredging or pile driving.
Question 6: What is the purpose of a 'rock outlet protection' or 'riprap apron' at the end of a culvert or pipe?
- To filter sediment from pipe discharge
- To dissipate the energy of high-velocity discharge and prevent scour of the receiving channel (Correct answer)
- To increase flow velocity through the culvert
- To prevent animals from entering the pipe
Correct answer: To dissipate the energy of high-velocity discharge and prevent scour of the receiving channel
Riprap aprons absorb the energy of concentrated pipe or channel discharge, preventing erosion of the channel bed and banks immediately downstream.
CEPSCI Construction Site BMPs and Implementation 2
What is the primary purpose of inlet protection (e.g., a filter sock or gravel bag around a storm drain inlet)?