CPWM Utility Systems 3

Question 1

What is the MINIMUM residual chlorine level the EPA recommends maintaining at the ends of a potable water distribution system?

Accepted Answer

0.2 mg/L

Answer

The EPA recommends a minimum residual disinfectant concentration of 0.2 mg/L at all points in the distribution system to prevent microbial regrowth.

Question 2

A public works manager is evaluating natural gas distribution system leaks. Which instrument is MOST appropriate for detecting methane in soil?

Accepted Answer

Combustible gas indicator (CGI)

Answer

A combustible gas indicator (CGI) detects the presence and concentration of flammable gases like methane, making it the standard tool for natural gas leak surveys.

Question 3

Secondary wastewater treatment primarily removes which type of pollutant?

Accepted Answer

Biological oxygen demand (BOD) through biological processes

Answer

Secondary treatment uses biological processes (activated sludge, trickling filters) to decompose dissolved and suspended organic matter, significantly reducing BOD.

Question 4

Which condition is MOST likely to cause water hammer in a distribution system?

Accepted Answer

Rapid pump shutdown or valve closure

Answer

Water hammer occurs when flow is suddenly stopped or reversed, creating pressure surges that can damage pipes, valves, and equipment.

Question 5

Under OSHA's confined space regulations, a manhole in a sanitary sewer system is MOST likely classified as a:

Accepted Answer

Permit-required confined space

Answer

Sewer manholes contain potential serious hazards including toxic gases (H₂S), oxygen deficiency, and engulfment risk, requiring a written permit for entry.

(CPWM) Certified Public Works Manager Practice Test

(CPWM) Certified Public Works Manager Practice Test

CPWM Utility Systems 3