1 Lake County WTP Improvements and Capacity Increase OTCO 9 th Annual Water and Wastewater Workshop 7.31.2013 Nick Pizzi Aqua Serv Rick Douglas Lake County
Presentation Agenda Some topics we will cover: Background and impetus for the upgrades A comparison of plant capabilities both before and after the upgrades Engineering considerations of the upgrade Pilot testing Technologies used Operational experiences of the upgraded facilities
History of the Bacon Road Plant The WTP went online in 1982 Plant was rated for 6 mgd Surface water treatment plant Lake Erie source Conventional treatment In the mid-2000 s, the WTP exceeded 6 mgd treatment rate on a number of occasions Ohio EPA required that the WTP study the possibility of an upgrade
Audit An audit was performed to determine which steps might be required for plant expansion and upgrade This audit: Assessed systems and processes based on ability to operate to at least 9 mgd a 50% increase The audit determined that: Higher rating needed and could be obtained for the filters Higher rating needed and could be obtained for sedimentation process Other upgrades were necessary: 2 raw water pumps needed to be upgraded Chemical feed systems needed some upgrades The need existed to:» Install new polymer feed systems (filter aid, thickener feed)» Improve residuals storage and handling» Improve residuals removal from sedimentation basins
Higher Rates for Processes Sedimentation The Ohio EPA did not require pilot-scale testing of sedimentation because Lake County agreed to install tube settlers The existing SOR of 0.46 gpm/ft 2 would be upgraded to 2.0 gpm/ft 2 with the installation Filtration Pilot-scale testing of filter configurations was required Three pilot columns were used for 4 two-week periods Turbidity and particle count data was collected, along with UFRV and head loss data A new configuration was approved at 5.7 gpm/ft 2
A brief graphical review of pilot facility The pilot created a way to produce operational data Data was collected that Ohio EPA could use in their determination of which filter configuration and filter rate they might approve
Constant Head Tank Settled Water Influent Line 3 Columns 3 Flow meters 4 Turbidimeters
Piloting Equipment
More Pilot Equipment Calibration of Turbidimeters Constant Head Tank
Left to right Column A (being backwashed), Column B, Control column
More details Rick with SCADA system Staff Backwashing Column B
Ohio EPA Approval Ultimately: Ohio EPA approved for filters: 24 inches of 1.1 mm anthracite, UC of 1.3 12 inches of 0.5 mm sand, UC of 1.3 Low profile filter bottoms (IMS caps) 9 mgd with one unit out of service For pretreatment: Tube settlers, rated at 2.0 gpm/ft 2
Lake County East Water Treatment Plant aka Bacon Road Water WTP B4 Upgrades Plant Capacity 6 mgd Source : Lake Erie 48 inch intake Intake Capacity 10 mgd Envirex travelling screens Potassium Permanganate feed After Upgrades Plant Capacity 9 mgd Source : Lake Erie 48 inch intake Intake Capacity 10 mgd Envirex travelling screens Potassium Permanganate feed The intake and structures were fine, but raw water pumps were increased VFD s
Some of the Bacon Road WTP Raw Water Station Units Raw Water Pumps New VFD Drives Two of the four old raw water pumps There is a VFD controller and two new VFD pump units. The pumps are rated at 2,604 gpm for the two VFD units, and 1,750 and 3,500 gpm for the other two units. Therefore, the firm capacity is 1,750 gpm + 2,604 gpm + 2,604 gpm, or 6,958 gpm (10 mgd).
Some of the Bacon Road WTP Raw Water Station Units Travelling Screens Permanganate System Envirex traveling units that are washed free of debris by using water from the pump discharge line 240 gallon day tank and a dual set of peristaltic pumps which feed the KMnO 4 solution down into the screen wells. The range of each pump is 0-200 rpm, and each will pump a maximum solution feed rate of 250 mls/minute.
Bacon Road WTP Treatment Units Rapid Mixers B4 2 units, 1,060 gallons each, DT@ 6 mgd = 30 seconds G value 30 0 sec -1 Rapid Mixers After 2 units, 1,060 gallons each, DT@ 9 mgd = 20 seconds G value 300 sec -1 Note: alum/polymer blend feed point
Bacon Road WTP Treatment Units Flocculators B4 2 units, 62,000 gallons each, DT@ 6 mgd = 30 minutes Three compartments / tapered paddle mixing G value 60, 50, 40 sec -1 Flocculators After 2 units, 62,000 gallons each, DT@ 9 mgd = 20 minutes Three compartments / tapered paddle mixing G value 60, 50, 40 sec -1 Note: Activated Carbon feed
Bacon Road WTP Treatment Units Sedimentation B4 2 units, 500,000 gals each, DT @ 6 mgd = 4 hours 4,500 ft 2 SOR = 0.46 gpm/ft 2 WOR 10,000 gal/day/ft Sedimentation After 2 units, 500,000 gals each, DT @ 9 mgd = 2.67 hours Tubes = 2 by 2 and three feet long, so 5,400 ft 3 Design SOR = 0.2 gpm/ft 2 (or 2.33 times slower than the old 0.46 rating) WOR 15,600 gal/day/ft Nominal capacity is about 7 mgd per unit
Sedimentation Retrofit process improvements and residuals removal Tubes Weirs Baffle wall Sludge collection system
Sedimentation: old vs. new Old Sed Basins side view Basin issues included Incomplete sludge removal / sludge septicity Difficulty in dewatering the basin Conservative SOR Retrofitted Sed Basins side view Problems eliminated: Improved sludge removal mechanism Pump installed for dewatering Tubes installed allowing for higher rating Water enters through ports Siphons Baffle wall Sludge settles on slanted wall Sludge siphons travelled only from end of basin to slanted wall Cable driven sludge collector Scrapers and siphons There are no drains in these basins had to use sump to dewater 20
Sedimentation Basin Graphic Inlet ports Slanted wall New sludge lines being installed for sludge removal and basin dewatering New Sludge removal equipment being installed
Baffle Wall Installation Inlet ports Support for Tubes Baffle
Tube Settlers Weirs Tube cover system allows operators to walk across
Sedimentation Basin Operations MRI sludge collectors remove solids more efficiently than original flotation system No more sludge buildup at basin influent slanted wall Sedimentation basins are no longer used for sludge storage Use of the rotary lobe pump with sludge collectors dewaters the basins, eliminating the need to use a sump pump (increased safety) Tube settlers are easily cleaned with a garden hose A Core-Pro tool is used to study the depth of sludge, which provides a profile that we use to program sludge collector timing/run patterns
Basin Sludge Sampling
Bacon Road WTP Treatment Units Filtration B4 Four filters, 363 ft 2 each rated at 1.5 mgd each This is a 3 gpm/ft 2 filter rate with all units in service Dual-media configuration with torpedo sand and gravel support and Leopold bottoms Configured with 18 inches of 0.9 mm anthracite, and 12 inches of 0.5 mm sand Uniformity Coefficient of 1.7 Filtration After Four filters, 363 ft 2 each rated at 3 mgd each with 1 unit out of service Dual-media configuration with low profile IMS caps which provided additional 7 inches of depth for media Configured with 24 inches 1.1 mm anthracite, and 12 inches 0.5 mm sand Key: Each with a 1.3 uniformity coefficient
Filter Construction Issues Filter retrofit activities had to be planned around operations Old conical Wheeler bottom tiles had to be jack-hammered out A 2-inch concrete lip was found around the entire perimeter of each filter bottom Not shown on original prints Another sub-contractor had to come in with diamond bladed saws to remove this lip prior to installation of new IMS caps
Filter Construction
Filter Construction
Filter Configuration Filter # ES Sand ES Anthracite D90 size Anthracite D90/D10 ratio 1 0.50 1.11 1.68 3.40 2 0.54 1.14 1.67 3.09 3 0.50 1.10 1.59 3.40 4 0.50 1.10 1.67 3.35 When the new media was installed into the filters, each layer was backwashed repeatedly and scraped to remove fines, and then sampled for lab analysis The table above shows the as built filter configuration for the new dual-media units built in the fall/winter of 2011 Note that filter #2 was scraped slightly more than the other three filters
Backwash Capability A pump from the High Service Header supplies the tank - Pump is rated at 500 gpm Filters can also be washed from the Header under emergency Washwater Storage Tank Spent filter backwash Water collected and pumped To lagoon conditions The tank holds 300,000 gallons There are dual-level surface washers designed to scrub the surface and the interface of the filter
Current Filter Operations Achieving very good UFRV s With deeper beds, filter inspection via coring is important Solids retention profile helps to determine where solids are being removed, and if backwash is adequate Filter backwash problems when Washwater Storage Tank was O.O.S. for painting
Old Residuals System Small catch basin Old sludge pump Took in sludge from sedimentation Had a weir and telescoping valve. Supposed to be used as thickener. Sloped floor. System undersized. Moved sludge from catch basin to the lagoons. No provision for polymer.
Residuals Improvements Rotary Lobe Pump Double disc pumps Used for sludge transference and for basin dewatering 35 gpm each at 30 head Polymer system provided
New Thickeners 44,000 gallons each designed for 13 gpm @ 1.3% solids
Residuals Improvements Inside of Thickener Sludge Removal pumps Rake arm concentrates sludge to middle-bottom area of unit Thickened sludge sent to the lagoons
Sludge Thickener Ops Secchi in 13 feet of water Secchi
Typical Bacon Road Sludge Output For a daily flow of 2.7 MGD, and 30 mg/l Coagulant, 3 mg/l PAC, and 10 mg/l SS: Dry solids produced, S = (8.34Q) (0.44Al + SS + A) S = (8.34 X 2.7)((0.44 x (30 mg/l x 0.45) + 10 + 3)) S = (22.52)(5.94 + 10 + 3) = 22.52 X 18.94 = 426.5 pounds per day That s about 78 Tons dry solids per year
Residuals Operations Diaphragm Pumps If solids are too thin, pumps will lose efficiency because air chamber fills with liquid Thickeners Good idea to use a secchi disk for observing clarity/depth in thickener Polymer Feeder Must ensure that there is sufficient room for polymer aging Operator involvement and education is important Operators like to speak in terms of mg/l, but need to learn concept of lbs polymer / dry ton solids
Residuals Operations Polymer Use Anionic polymer is used Comes in 40 pound bags granular from must be aged made up to about 0.2 to 0.25% If WTP produces 78 tons of dry solids per year, and polymer use is 3.5 pounds per dry ton: 78 tons X 3.5 lbs / ton = 273 pounds of polymer per year, or about 7 bags
NPDES West Lagoon East Lagoon Rotary sludge pumps Thickeners Old dewatering discharge pipe from basins SFBW Sludge pumps and sludge well with mixer Sedimentation basin sludge
Sludge lagoon
Polymer Feed Improvements Filter aid Sludge thickening Operational goal: use if sed basin ntu >2.5, or if filter effluent turbidity is increasing. Design: 3.5 lbs per ton dry solids. Hot water tank provided.
Acknowledgements Thanks to Rick Martin and Randy Rothlisberger of Lake County Utilities Thanks to Dave Cornwell and Gerry Wright of EE&T Any Questions?