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

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

Overview of Existing Plant 01 Overview of Existing Plant

First Broad River WWTP Permitted for 6 mgd Current avg flows 2.75 mgd prior to new industry (2009-2012) 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

First Broad River WWTP Process Flow Diagram Polishing Aeration Basin

Revised Ammonia Permit Limits 02 Revised Ammonia Permit Limits

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

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

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

Ammonia Removal Upgrades Project 03 Ammonia Removal Upgrades Project

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

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

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

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.

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

Construction Sequencing 04 Construction Sequencing

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)

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

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

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

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

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

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)

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

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

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

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

Summary and Conclusions 05 Summary and Conclusions

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

Questions?