Inspection Monitoring & Maintenance Procedures Flashcards

A stormwater manager is reviewing inspection records for a sand filter BMP and notes that drawdown time after storms has increased from 12 hours (design) to 72+ hours. This condition indicates:

Answer: Filter media clogging requiring surface scarification, replacement of the top layer, or full media replacement

Prolonged drawdown in a sand filter indicates clogged media that is impeding infiltration; the filter requires maintenance (scarification or media replacement) to restore design permeability.

When collecting stormwater runoff samples for laboratory analysis under an industrial stormwater permit, which sample type is REQUIRED for conventional pollutants under most EPA industrial general permits?

Answer: Flow-weighted or time-weighted composite samples collected during a qualifying storm event

Industrial stormwater general permits (Multi-Sector General Permit) typically require composite or grab samples collected during qualifying storm events to capture actual discharge quality.

An inspector evaluating a green roof system observes that drainage layer outlets are discharging continuously between storm events. What does this condition most likely indicate?

Answer: A water supply irrigation system leak or rooftop ponding creating a chronic drainage issue

Continuous discharge between storms from a green roof suggests either a leaking irrigation supply line or persistent ponding that indicates media compaction or drainage layer blockage.

Which of the following conditions observed during inspection of a stormwater pipe network would be classified as a 'structurally significant defect' requiring priority repair?

Answer: Joint offset of more than 20% of pipe diameter with visible soil intrusion

A joint offset exceeding 20% of pipe diameter with soil intrusion indicates imminent risk of sinkhole formation or pipe collapse and requires urgent structural repair.

A CSM is developing a maintenance agreement for a privately owned stormwater pond serving a residential subdivision. Which element is MOST critical to include to ensure long-term performance?

Answer: Enforceable inspection frequency requirements, maintenance standards, and access rights for municipal oversight

A maintenance agreement must include enforceable minimum performance standards, inspection schedules, and municipal access rights to ensure the BMP functions over its design life and regulators can verify compliance.

During inspection of a constructed wetland stormwater BMP, an inspector observes that cattails have completely monoculturalized the system, eliminating open water zones. What maintenance response is appropriate?

Answer: Mechanical or herbicide treatment to restore the design ratio of emergent vegetation to open water (typically 50/50)

Constructed wetland design requires alternating zones of emergent vegetation and open water for sediment settling and habitat; cattail monocultures reduce hydraulic efficiency and must be managed.

A stormwater monitoring program uses automated data loggers to record stage (water level) in a detention pond at 15-minute intervals. What is the PRIMARY value of this continuous data record?

Answer: It enables calculation of inflow/outflow hydrographs and identification of outlet performance problems between manual inspections

Continuous stage data allows derivation of inflow and outflow volumes, detection of outlet blockage (abnormally slow drawdown), and comparison of actual versus design hydraulic performance.