Tuckaseigee Water and Sewer Authority

Transcription

1 NORTH CAROLINA AWWA-WEA SPRING CONFERENCE ASHEVILLE, NORTH CAROLINA APRIL 18, 2016 Tuckaseigee Water and Sewer Authority Expands with a 3.5 MGD SBR Wastewater Treatment Facility and Sludge Dryer Stanley Bryson, TWSA Mike Waresak, PE, McGill Associates, PA

2 Presentation Outline TWSA Background Need for Facility Improvements Planning and Discharge Permit Process Design and Performance Construction Sequencing Challenges Sludge Drying System and Costs

3 TWSA Background TWSA: Established in 1992 to consolidate Jackson County public water and sewer systems TWSA operates 4 Wastewater Treatment Plants and 1 Water Treatment Plant WWTP No. 1 Service Area: Sylva, Dillsboro, Cullowhee, including WCU WCU: Approx. 10,000 students

4 .cullowhee I-

5 WWTP No. 1 Prior to Upgrades

6 Need for Facility Improvements Planned developments and WCU expansions potential for higher flows WWTP No. 1 incapable of treating 1.5 mgd NPDES permit violations BOD, TSS, fecal coliform Treatment limitations due to aeration basins (low detention time) and shallow rectangular clarifiers Poor influent screening and grit removal Lime pasteurization system issues

7 Planning and Funding Special Order by Consent with NCDEQ Expand to 3.5 mgd Tuckasegee River - aquatic wildlife Headworks, SBR, Post EQ, Chlor/Dechlor, Sludge Dryer Funding: USDA-RD, NCDEQ, CWMTF, Rural Center, TWSA $14.65 million

8 Discharge Permit Constraints Tuckasegee River NPDES Permit Parameter Monthly Avg Limit Weekly Avg Limit Biochemical Oxygen Demand (BOD) 30 mg/l 45 mg/l Total Suspended Solids (TSS) 30 mg/l 45 mg/l Ammonia Nitrogen (New discharge limit) 22.4 mg/l 35 mg/l Fecal Coliform 200 per 100 ml 400 per 100 ml Max Chlorine Residual 28 ug/l (Daily Max) Discharge Flow 3.5 MGD N/A

9 PROPOSED SOL IDS HANDLING / LABORATORY 8 U LOING PROPOSED SBR TREATMENT UNIT CONVERT CHLORINE \, ' ' CONVERT EXISTINGAERATION BASIN ',., TO NEW POST EQUALIZATION BASIN '\..,. ONVERT EXISTING CLARIFIERl,ro > NEW CH LOR IN E CONTACT BASIN) PROPOSED HEADWORKS WITH BAR SCREEN. GRIT REMOVAL AND INFLUENT PUMP STATION CONVERT " ""NG EQUALIZATION BASIN TO NEW DIGESTER F / /.., / / / / NG / / / //'< SERW>< / / / If' \ \

10 ll.w. JOISJ O SBRBASN#:l / - l- li1il llll- - 1_/- -7 -'/ / rwzou.m Sl.UOG! lank HOC.DOIG A<lti C.IJ..H.RAQOI E:l!tlUJ: -.-,..!IJ7,8' :.x&stt:nc SLUDGE HOLOlNC TN<K Jna.EL!Jlll.64 POST EO. BASIN ClllUICllDtAOOll IKITT1llil EL"."m"4.l6 POST AfM.TlON BASIN EllSfllfil CHl. 'illf C:Q'H,o,tl EW r.waoio.h PLOW MfASVRfMfNT PARSHALL f\u ME IS 9, O!ITFJ LTO n.a<asegee RIVER Bl- ' / Sl.UllGE PUMP STATK)H f )JSTt«l 6ELTFl.T R FRESS. TRPLEX P\lMP SYSTEM NO'!I:M.W.l.HIQMICATUtU\tl.I ATl'&Mf\.OWOfl,7$MGO

11 CONSTRUCTION SEQUENCING CHALLENGES

12 Plant Operation During Construction Bypass existing aeration and clarifier. Operate with 1 SBR, discharge to existing chlorine contract basin. Throttle decant valve to reduce discharge rate. Convert existing aeration/clarifier to Post EQ /chlorine contact.

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15 Plant Performance During Construction Parameter Plant Effluent (1 SBR in operation) Biochemical Oxygen Demand (BOD) 26 mg/l 40 mg/l 16 mg/l Total Suspended Solids (TSS) 23 mg/l 33 mg/l 18 mg/l Fecal Coliform 10#/100ml 60#/100ml 48#/100ml Avg. Plant Effluent (2 SBRs in operation)

16 PROJECT PHOTOGRAPHS

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18 Large SBR Basins Precast Post-Tensioned Concrete Tanks 112 feet diameter 1.7 MG each Precast concrete wall panels HDPE Horizontal Ducts embedded in panels for post-tensioning strands

19 Precast Post-Tensioned SBR Basins

20 SBR Mixing Equipment

21 SBR Basin and Aeration Blower Building

22 SBR Aeration Blowers

23 Performance Effluent Quality Parameter Effluent Prior to Improvements (Monthly Avg) Biochemical Oxygen Demand (BOD) 27 mg/l 5.6 mg/l Total Suspended Solids (TSS) 27 mg/l 3.8 mg/l Ammonia Nitrogen N/A 1.3 mg/l (New discharge limit) Fecal Coliform 60 per 100 ml 14.3 per 100 ml Discharge Flow 1.0 MGD 0.80 MGD Effluent After Improvements (Monthly Avg)

24 Sludge Drying System Class A Product meeting 40 CFR part 503 regulations Product distributed to public 3,500 dry lbs per hour capacity

25 Sludge Drying System Sludge Dehydration System Natural Gas Dewatered Sludge from 1.0 Meter Belt Press Hot Oil Heat Exchanger Mbtus Dried Solids Storage Silo

26 rb 1;'n1'"\ t'111"-' l a I I. t'.4 J L..-Q I!.,.. ;., -..:

27 Sludge Dryer/Lab Building

28 Sludge Drying Equipment Room

29 Sludge Drying Operating Costs Description Lime Pasteurization Sludge Drying Sludge Processed 127 dry tons/yr. 280 dry tons/yr. Belt Press & Polymer $109/dry ton/yr. $100/dry ton/yr. Lime Cost $215/dry ton/yr. N/A Natural Gas Cost N/A $111/dry ton/yr. Dryer Operator Labor Cost N/A $58/dry ton/yr. Total $324/dry ton $269/dry ton

30 TWSA Class A Biosolids Product Greater than 90% solids Approximate fertilizer value: 1.4 N, 2.0 P, 0.4 K Final disposal options

31 Conclusions SBR is a good process fit due to site restrictions. Maintaining plant operation during construction requires careful thought and close coordination with contractor. SBR produces excellent effluent. For TWSA, sludge drying has proved to be less costly than lime pasteurization.

32 Questions? Stanley Bryson, TWSA Mike Waresak, PE, McGill Associates, P.A.