Welcome! Water & Wastewater Utility Operation and Management for Tribes

Welcome! Water & Wastewater Utility Operation and Management for Tribes

Introductory Case Studies Water & Wastewater Utility Operation and Management for Tribes

Water System Pesticide Contamination 1. Lawn care worker connects to a hydrant to fill his truck and create a herbicide mixture for use on a clients lawns

Water System Pesticide Contamination 2. Worker goes inside office while tank is filling and gets distracted 3. The office is located on dead end street next to bakery 4. Water department performing routine maintenance at the same time and shuts water off on the street

Water System Pesticide Contamination What do you think happens?

Water System Pesticide Contamination Answer: Loss of pressure in the main sucks the chemical from the tank back into the water line.

Water System Pesticide Contamination When water is restored, bakery notices a taste and odor in the water.

Water System Pesticide Contamination What should be done?

Water System Pesticide Contamination After Effects: Water Department sampling determined chemical contamination Water flushed using hydrants ww.blendontwp.org/ Copyright 2007, All Rights Reserved Tualatin Valley Water District

Water System Pesticide Contamination After Effects: Contaminated Equipment disposed of Continue sampling until no chemical detected http://www.coffee-maker-review.net

Water System Pesticide Contamination What lessons can be learned? Don t leave vehicles unattended during potentially dangerous procedures Make sure backflow prevention devices are in place, especially when connecting to a hydrant Consider how you notify customers of an interruption in water supply

Water Treatment Plant Chemical Contamination 1. Sodium Hydroxide used at plant for ph adjustment 2. Worker switches the manual override on chemical feed system to ON to complete a task in another area of plant

Water Treatment Plant Chemical Contamination 1. Sodium Hydroxide pumps with day tank

Water Treatment Plant Chemical Contamination 2. The worker leaves the room to start next task, and forgets to turn manual override system off 3. Chemical continues to feed triggering alarm

Water Treatment Plant Chemical Contamination 4. Alarm is tied into SCADA, which controls alarm signals 5. Receptionist at plant unplugs the SCADA to connect the fax machine and forgets to plug it back in

Water Treatment Plant Chemical Contamination What do you think happens?

Water Treatment Plant Chemical Contamination Chemical is discharged to the system without the plant knowing EMS calls rise as local residents get chemical burns

Water Treatment Plant Chemical Contamination What should be done?

Water Treatment Plant Chemical Contamination Next Steps for Operator: Inspect the plant and turn chemical feed off Issue a Do Not Use order Flush hydrants in distribution system http://networkedblogs.com http://utilities.columbus.gov/seasonalspring.htm

Water Treatment Plant Chemical Contamination What lessons can be learned? Leave automated systems on Do not leave manual feed unattended Provide dedicated phone service for critical devices such as SCADA systems Install timer on manual override switches

Sewage Collection System Wastewater Overflow 1. Private sewage collection system extended into newly developed area 2. Some homes are occupied, some are under construction. 3. Debris builds up in downstream manhole, sewage begins to backup upstream towards cleanout

Sewage Collection System Wastewater Overflow What do you think happens?

Sewage Collection System Wastewater Overflow Sewage overflows out of cleanout and into nearby stormwater catchbasin discharging into woods

Sewage Collection System Wastewater Overflow

Sewage Collection System Wastewater Overflow DEBRIS BUILDUP CATCHBASIN CAPTURES WASTEWATER OVERFLOW OVERLAND DISCHARGE TO WOODS CLEANOUT BACKUP

Sewage Collection System Wastewater Overflow What should be done?

Sewage Collection System Wastewater Overflow What are the operators next steps: Neighbors identify sewage overflow and report to utility Utility investigates and clears blockage in manhole Utility reports overflow to regulatory agency 2011 scottscreekwatershed.org http://marshvillenc.govoffice2.com

Sewage Collection System Wastewater Overflow What lessons can be learned? Areas under construction with active collection system should be inspected frequently Erosion control measures at construction sites should be inspected prior to construction Identify low point of collection system and inspect regularly Develop a schedule for manhole inspection

Wastewater Treatment System Operation 1. A wastewater treatment system is designed for a flow of 7,000 gallons per day (gpd), however, the system is only receiving 2,000 gpd based on water use data 2. The system consists of primary settling tanks, a trickling filter system, effluent pump chamber and effluent disposal. 3. A portion of the effluent from the trickling filter is recycled to the primary tanks

Wastewater Treatment System Operation Primary Settling Trickling Filter Effluent Pump Chamber

System Layout Wastewater Treatment System Operation Trickling Filter Effluent Pump Chamber Primary Settling

Wastewater Treatment System Operation 4. With the treatment system components oversized for the design flow, the system is struggling to meet the permitted nitrogen discharge requirement of 25 mg/l 5. A portion of the biological treatment component is located outside, above grade 6. The treatment system is located in a climate where the wind chill levels in the winter can be below zero 7. The system has no chemical feed component

Wastewater Treatment System Operation What do you think happens?

Wastewater Treatment System Operation 35.00 30.00 25.00 Regulatory Target 20.00 15.00 10.00 5.00 0.00 7/6/09 10/14/09 1/22/10 5/2/10 8/10/10 11/18/10 2/26/11 6/6/11

Wastewater Treatment System Operation What should be done?

Wastewater Treatment System Operation What should operator do? Install smaller vent fan in winter to reduce cold air intake Increase recycle rate to bring more nitrified wastewater into anaerobic primary tank for denitrification Add supplemental carbon source to increase food supply for bugs