1. Construction OF AMMONIA REMOVAL UPGRADES FOR FIRST BROAD RIVER WWTP
David Hux, City of Shelby;
Will Shull, Mary Knosby, and Christopher Crotwell, HDR
2015 NC AWWA WEA Annual Conference
November 17, 2015, Raleigh

2. 01 04 02 05 03 Topics for Today’s Presentation
Overview of Existing Plant 04
Construction Sequencing 02
Revised Ammonia Permit Limits 05
Summary and Conclusions 03
Ammonia Removal Upgrades Project

3. Overview of Existing Plant01
Overview of Existing Plant

4. First Broad River WWTP Permitted for 6 mgd
Current avg flows
2.75 mgd prior to new industry ( )
Approx. 3.5 mgd with new industry
Originally constructed in 1960’s
Trickling Filter Plant
Upgraded in 1993
Added polishing activated sludge aeration basins
Two 0.75 MG aeration basins
Jet pod aeration system
Not sized for nitrification

5. First Broad River WWTP Process Flow Diagram
Polishing Aeration Basin

6. Revised Ammonia Permit Limits02
Revised Ammonia Permit Limits

7. Revised Ammonia Permit Limit
2010 Permit Renewal included revised ammonia permit limits
Summer Monthly average NH3-N
From 18.5 mg/L to 4.7 mg/L
Summer Weekly average NH3-N
From 35 mg/L to 14.1 mg/L
Based on DWR’s current ammonia policy
1 mg/L summer in-stream NH3-N
Permit notes “EPA’s recent proposal have the potential to lower ammonia criteria further”
6-year compliance schedule provided
YAD1391A

8. Current Effluent NH3-N Performance
WWTP upgrades required to meet revised ammonia limit

9. NPDES Permit Limit Summary
Parameter
Monthly Average
Weekly Average
Daily Max
Flow (mgd)
6.0 -
BOD5 (mg/L) 25
37.5
TSS (mg/L) 30 45
Ammonia-N (Summer) (mg/L)
4.7
14.1
Ammonia-N (Winter) (mg/L)
18.5 35
Fecal Coliform
200/100 mL
400/100 mL
TRC (mg/L)
28 µg/L pH
>6.0 pH < 9.0 standard units
Total Nickel
261 µg/L
NPDES Permit Limit Summary

10. Ammonia Removal Upgrades Project03
Ammonia Removal Upgrades Project

11. Project Goals Upgrade biological treatment process
Enhance nitrification to meet more stringent ammonia limits
Repair and replace several deficient treatment components
Improve treatment reliability
Accommodate flows up to the permitted capacity of 6.0 mgd.
Meet project schedule requirements for Clean Water State Revolving Fund (CWSRF) program

12. Biological Treatment Process Upgrades
Convert existing process to conventional activated sludge system
Decommission trickling filters
Add third 0.75 MG aeration basin
Replace jet pods with fine bubble diffusers
Provide additional blower capacity
Add baffles / mixers for pre-anoxic zone
For denitrification and alkalinity recovery

13. Construction of Aeration Basin 3
October 2014
September 2015
Add third 0.75 MG aeration basin
August 2014
March 2015

14. Construction of Aeration Basin 3
Replace Existing DIP Air Header with Stainless Steel
Route Stainless Steel Air Header under Walkway
Add third 0.75 MG aeration basin
Accounting for the design details (SS Piping) but not overlooking the little details such as providing the City with plenty of walkway access by routing piping under the walkway. Less cluttered.

15. New MLE Process Anoxic / Internal Recycle Discharge / Mixers Aerobic
(Fine Bubble)
Aerobic
(Fine Bubble)
Aerobic (Fine Bubble)
Internal Recycle Suction
FLOW IR
Add third 0.75 MG aeration basin
Provide additional blower capacity
Add baffles / mixers for pre-anoxic zone
For denitrification and alkalinity recovery
Zone 1, Cell A
Zone 2
Zone 3
Zones 4 & 5

16. Construction Sequencing04
Construction Sequencing

17. Construction Sequencing
Maintenance of Plant Operation
Identity threats to operation
Duration
Coordination
Contingency Plan
Communication is vital to success
Realize that plant must continue operation and maintain permit limits while getting the job done.
All parties present, talk through as if it were happening now.
Potential Threats to Operation
-Rain (=High Flows), Compost/BFP, Industry (Clearwater)
Duration (how long it the shutdown, tie-in expected to take)(how long can the City Manage
Coordination
Contingency Plan (Pumps, Generator, etc on standby)

18. AB Splitter Box Phasing
PC1
How to install while continuing plant operation?
PC2

19. AB Splitter Box Phasing
PC1
TF1
How to install while continuing plant operation?
Put trickling filters back into service
How is the plant going to react
PC2
TF2

20. AB Splitter Box Phasing
PC1
How to install while continuing plant operation?
Put trickling filters back into service
How is the plant going to react
PC2
ABSB

21. WAS Pump Station Conversion
Self-priming centrifugal to non-clog submersible
Selective demolition of structure
Valve vault installation

22. WAS Pump Station Conversion
Phasing Challenges
How can we waste?
Temporary bypass?
Conflicts with trickling filter
Solution
Pump to existing thickener with new pumps
Similar heads and flow rates to existing system

23. Blower Upgrades Positive displacement to Turblex variable diffuser
More control
More efficient
Replace ductile iron with stainless steel piping
Installed 3 new turblex blowers (2 duty, 1 standby)

24. Blower Upgrades Phasing challenges Phasing Solutions
Existing room full of blowers
Keep plant operational
Phasing Solutions
Route new piping overhead
Short coordinated shutdown
MOPO led to solution

25. Blower Upgrades Startup challenges Proposed Solutions
Lower flows (less I&I)
One AB in operation during retrofit
Trouble meeting low air demand
Proposed Solutions
Waste to atm. via header blow-off valve
Incomplete blower function
Waste to atm. via AB2 header
Noise pollution
Waste to AB3 via AB2 header
Introduce coarse Bubble but little effect on DO
MOPO led to solution

26. Repair and Replacement Upgrades
Replace Influent Screen
Recondition Clarifiers No. 1 and 2 and replace drive units, weirs, bridges and scrapers
Replace and upgrade RAS pumps
Rehab Primary Clarifiers

27. Repair and Replacement Upgrades, Cont’d
Install new 40-ft Gravity Thickener
Install new Thickened WAS Pump Station
Rehab 26-ft Gravity Thickeners and convert to Belt Filter Press Filtrate EQ
Rehab Sludge Holding Tank

28. Summary and Conclusions05
Summary and Conclusions

29. Summary and Conclusions
Ammonia upgrades provide future flexibility
Accounts for future industrial changes
Positioned for potentially more stringent effluent NH3-N limit
Other upgrades will improve overall process reliability
Better process control (ie, RAS / WAS pumping)
Equalize side stream flows (filtrate EQ)
Communication is vital to a projects success

30. Questions?