1. DENVER ZOO Lion’s Quarters Recycle Cross-connection
Fred J. Sanchez
Denver Water, Water Quality Investigations Supervisor

2. AGENDA CROSS-CONN @ THE DENVER ZOO RECYCLE SYSTEM OVERVIEW
BACKGROUND INFORMATION
INCIDENT DESCRIPTION
ACTIONS TAKEN
INVESTIGATION RESULTS
CORRECTIVE MEASURES

3. Acknowledgments My personal friend… Water Quality Personnel
WQ Investigations
Cross-connections
Water Control Personnel
Emergency Services
System Quality
Denver Zoo Personnel
VP for Planning
Zoo Staff
My personal friend…

5. DENVER WATER’S RECYCLE SYSTEM
Metro Wastewater Reclamation provides Denver Water’s Recycle Plant with source water
The source is further treated by Denver Water
Biological Nitrification
Chemical Coagulation
Flocculation
Granular Media Filtration
Chlorine Disinfection
DW provides both potable & recycled water to the Denver Zoo

6. DENVER ZOO’S RECYCLE SYSTEM
Takes recycled water from Denver Water’s Recycling Distribution System
Supplied by the Zoo’s Pump Station
Owned & Operated by the Zoo
Primary use…
Wash Down purposes in the animal pens

7. DENVER WATER’S RECYCLE SYSTEM PHASE I MAP
METRO WASTE WATER
DW RECYCLE PLANT
DENVER ZOO

8. LNQ’S BACKGROUND INFORMATION
Both Potable & Recycle lines are located in the LNQ’S Mechanical Room
The potable & recycle water entering the mechanical room have separate services
Potable is used for animal food prep, employee wash room, and hose bibs.
Recycle is primarily used for wash down purposes in the Lion’s holding quarters since May 2005.

9. LNQ’S RECYCLE & POTABLE SYSTEM
RECYCLE LINE
LION’S WASH-DOWN LINE
PHYSICAL SEPARATION
POTABLE SERVICE WATER

10. INCIDENT DESRIPTION February 27, 2006 Conceptual Plan
DW scheduled a meeting with Zoo staff
Discuss a means of temporarily supplying the Zoo’s recycle system with potable water
Accommodate recycle system construction
Conceptual Plan
Physically disconnect the ‘recycled source’ at LNQ
2-Inch Diameter Pipe
Cut & Cap
Connect the ‘potable line’ as the new source protected by a Reduced Pressured Zoned Backflow Prevention Device (RPZ)

11. INCIDENT... During the meeting on Feb 27th
DW discovered the conversion was done incorrectly
A direct “Cross-connection” between the potable & recycled water lines was created
The Zoo’s pump station was operating during the discovery

12. CROSS-CONNECTION
RECYCLE LINE
CROSS-CONNECTION
POTABLE SERVICE WATER

13. ACTIONS TAKEN
Denver Water Personnel & Zoo Personnel surveyed the potable system for contaminated drinking water (Recycle)
Used Specific Conductance Meters (µS)
Potable Source = 300 µS
Recycle Source = 700 – 900 µS

14. ACTIONS… Utilized Zoo’s Engineering Drawings & Tested Conductivity
Fire Hydrants
Water Fountains
Sink Taps
Potable Water Service Lines
DW’s Distribution System
Outside Zoo’s property

15. ACTIONS… Collected bacteriological samples
Drinking Fountains
Break Room Taps
Food Vendors
Pending the bacteriological results
DW recommended isolating the Zoo’s system
Prevent public contact with the drinking water until further notice
No Human Consumption

16. INVESTIGATION RESULTS
The conductivity results showed
Small portion of the Zoo’s potable system was contaminated with Recycle water
LNQ’s Domestic Service Line
3-inch diameter x 345-ft
Zoo’s Distribution Main
Service to the LNQ bldg.
8-inch diameter x 30-ft

17. Zoo's POTABLE DISTRIBUTION SYSTEM
CONTAMINATED SERVICE

18. CONTAMINATED SERVICE LINE & WATER MAIN

19. CORRECTIVE MEASURES
Remove the Cross-connection between the Potable & Recycle Line
Physically separate the two systems

20. APPROVED PHYSICAL SEPARATION
RECYCLE LINE
APPROVED SEPARATION
POTABLE SERVICE WATER

21. CORRECTIVE MEASURES…
Flush, Disinfect, Test Contaminated Service Lines & Distribution Water Main
Ozonation Method = 1.0 mg/L Dosage
Kills Pathogenic Organisms
Kills Cryptosporidium
Collected Bacteriological Samples
Service Lines
Distribution System Fire Hydrant

22. CORRECTIVE MEASURES…
Ensure the Zoo complies with Recycle Water Regulations
Backflow Prevention
Marking & Signage
Create a Management of Change Protocol
Ensure Zoo staff & contractors have approval for future modifications
Provide additional training to Zoo staff
Regulations Requirements
Protect the public water system from contamination

23. CONCLUSION Most Important… The Cross-connection was removed
All bacteriological results from the initial water quality survey were negative
All bacteriological results from disinfection process were negative
The Zoo has “High Quality H20”
Most Important…

24. KEEP FRED’S FRIENDS LOCKED UP
MOST IMPORTANT
KEEP FRED’S FRIENDS LOCKED UP
“AT ALL TIMES”!

25. Q&A ?