Construction Site BMPs and Implementation Flashcards

Erosion control blankets (ECBs) are primarily used to:

Answer: Protect seeded slopes from rainfall impact and erosion until vegetation is established

ECBs provide physical protection of seeded soil from rainfall impact and surface runoff while vegetation germinates and establishes, after which the blanket may degrade or be removed.

What is the minimum recommended maintenance interval for silt fences under the US NPDES CGP?

Answer: At least every 7 business days and within 24 hours after a 0.25-inch or greater storm event

The NPDES Construction General Permit requires inspections at least every 7 business days and within 24 hours of qualifying rain events to ensure BMPs are functioning properly.

What is the purpose of a 'slope drain' or 'temporary slope drain pipe'?

Answer: To convey concentrated runoff down a slope without causing erosion by protecting the slope surface from flow

Slope drains are pipes anchored to the slope surface that convey concentrated runoff from the top to the bottom of a slope without allowing the flow to contact and erode the slope face.

Which of the following is an example of a 'good housekeeping' BMP on a construction site?

Answer: Properly storing and disposing of concrete washout water in a designated lined area

Good housekeeping practices manage materials, waste, and spills to prevent pollutants other than sediment — such as concrete, fuel, or paint — from reaching stormwater.

When is it appropriate to use polyacrylamide (PAM) as an erosion control amendment?

Answer: As a soil amendment applied to disturbed soils to reduce erosion, typically in conjunction with seeding and mulching

PAM is an anionic polymer that binds soil particles together, reducing erosion and improving water quality when applied to disturbed soils along with other BMPs.

What is the correct approach when a BMP is found to have failed or to be inadequate during an inspection?

Answer: Repair or replace the BMP as soon as practicable, typically within a defined timeframe required by the permit

Permits typically require prompt repair of failed BMPs, often within 24 hours or before the next rain event, to maintain continuous erosion and sediment control.