Stormwater Runoff Management Flashcards

A key principle of construction sequencing for minimizing erosion is to perform which of the following actions FIRST?

Answer: Install perimeter controls and sediment barriers before mass grading begins.

Proper construction sequencing requires that principal sediment and runoff control measures, such as perimeter controls (silt fences, berms) and sediment traps/barriers, be installed *before* major land-disturbing activities like mass grading commence. This ensures that a system is in place to capture sediment as soon as soil is exposed.

An inspector observes a dewatering operation where water from an excavation is being pumped through a geotextile filter bag. The bag is placed on a steep, un-stabilized slope and appears to be more than 75% full. Which of the following represents the MOST significant compliance concern?

Answer: Discharge from the bag could cause severe erosion on the un-stabilized slope.

While all options could be concerns, the most significant and immediate issue is the potential for the filtered water discharging from the bag to cause severe erosion on the steep, un-stabilized slope below it. Filter bags should be placed on nearly level surfaces (less than 5% slope) and the discharge must be directed to a stabilized area to prevent scouring and erosion.

What is the primary function of adding flocculants, such as polyacrylamide (PAM), to sediment-laden stormwater runoff?

Answer: To bind fine, suspended sediment particles together into larger clumps (flocs) that settle out more quickly.

Flocculants are chemical agents that cause fine, suspended particles like clays and silts to aggregate into larger, heavier clumps called flocs. This process, known as flocculation, dramatically increases the settling rate of these particles, enhancing the effectiveness of sediment traps, basins, and other control measures.

An inspector is reviewing a construction site in an arid region that has received no rainfall for over a month. The SWPPP allows for a reduced inspection frequency under these conditions. According to typical EPA CGP guidance for arid areas, what is the appropriate inspection schedule?

Answer: Inspections can be reduced to once per month and within 24 hours of a specified storm event.

For sites in arid, semi-arid, or drought-stricken areas, the EPA Construction General Permit (CGP) allows for a reduction in inspection frequency. The typical reduced schedule is once per month and within 24 hours of a storm event that produces 0.25 inches or more of rain. The SWPPP must document the period when this reduced frequency is being used.

What is the fundamental difference between a temporary construction phase BMP and a post-construction BMP?

Answer: Temporary BMPs are designed to be removed after final stabilization, whereas post-construction BMPs are permanent features for long-term stormwater management.

Temporary construction BMPs (e.g., silt fences, check dams) are installed to control erosion and sediment during active construction and are removed once the site is permanently stabilized. Post-construction BMPs (e.g., bioretention basins, permeable pavement) are permanent installations designed to manage stormwater runoff, in terms of both quality and quantity, for the life of the developed property.

A CESSWI is inspecting a site where the contractor has begun dewatering an excavation pit that has accumulated stormwater. The water is being discharged directly into a nearby storm drain inlet. According to the EPA's 2022 CGP, what is a required inspection frequency for this specific activity?

Answer: Once per day on any day there is a dewatering discharge.

The EPA's 2022 Construction General Permit (CGP) has specific requirements for dewatering activities. All sites discharging dewatering water must be inspected once per day on any day that a dewatering discharge is occurring. This is in addition to the regular weekly or bi-weekly site inspections.