Streamline - Fall 2013 - (Page 35)

Wastewater Math QUESTIONS BY DONNA LAWSON, WASTEWATER TECH II 1. Find the approximate detention time in hours for the following water system: A 10-inch distribution pipe extends from the water plant to the storage tank 2,015 feet. The storage tank maintains 1,500,000 gallons. The system has a daily use of 2.45 MGD. a. 3 hours b. 10.5 hours c. 15 hours d. 24 hours A 6-inch water line needs to be flushed for compliance. If the line is 540 ft, about how long will it take to completely flush the line at a flow of 10 gpm? a. 22 minutes b. 50 minutes c. 80 minutes d. 1 hour and 20 minutes 2. 3. Calculate the specific gravity for a ferric chloride solution that weighs 10.02 lbs/gal? a. 1.02 b. 1.20 c. 1.31 d. 1.41 A water treatment plant produces 3.2 MGD that has a chlorine dosage of 2.4 mg/L entering the distribution system. The storage tank 4 miles away is receiving a chlorine residual of 1.9 mg/L. What is the chlorine demand of the distribution system between the plant and the tank? a. 0.5 mg/L b. 0.8 mg/L c. 2.4 mg/L d. 4.3 mg/L 4. 5. A 2,000,000 gallon storage tank must be disinfected using calcium hypochlorite (65.9 % available strength). The tank has to be filled to 15% capacity and achieve an initial chlorine residual of 20 mg/L. How many pounds of calcium hypochlorite will the distribution crew need to use? a. 15 lbs b. 32.3 lbs c. 65.9 lbs d. 76 lbs Answers on page 36 • Water Resource Planning • Groundwater Exploration & Well Rehabilitation • Geophysical Investigations • Aquifer Testing & Modeling • Dam & Reservoir Design 804.358.7900 (434) 372-3393 w w w . g o l d e r. c o m 638862_BB_Consultants.indd 1 5/7/13 7:57 PM 421675_Golder.indd 1 3/5/09 8:56:04 PM 646099_Draper.indd 1 w w w . v r w a . o r g 35 AM 25/06/13 6:44

Table of Contents for the Digital Edition of Streamline - Fall 2013

From the President
From the Executive Director
Acronyms – Today’s Language
Drought or Flood?
Can Changing Your Plant Lighting Save You Money?
Source Water Protection Notes
Aging and Failing Infrastructure
Time for Some R&R
EXPO Coverage and Recap
Ergs, Joules and Other Stuff
Wastewater Math
Throwing My Loop
eLearning Benefi ts
Membership Application
Do You Know What Your VRWA Benefi ts Are
Welcome New Members
VRWA Mailbag
Board of Directors
VRWA Committees
Index to Advertisers/

Streamline - Fall 2013