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Reclaimed Water Solution for Disposal Capacity Village of Bald Head Island 2015 NC AWWA - WEA Annual Conference November 17, 2015
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Bald Head Island Brunswick County Columbus County New Hanover County Bladen County Brunswick County Pender County North Carolina Bald Head Island
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History & Project Drivers 0.4 MGD SBR Wastewater Treatment Facility - Original owner Bald Head Island Utilities (private) - Low pressure collection system - 3 High Rate Infiltration (HRI) Basins - HRI basins permitted at 0.8 MGD disposal capacity WWTP HRI Basin 3 HRI Basin 2 HRI Basin 1
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History & Project Drivers Utility Ownership Transferred to Village of Bald Head Island - Transfer occurred late 90’s - Contractual obligation - island build-out capacity WWTP HRI Basin 3 HRI Basin 2 HRI Basin 1
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HRI Basin 3 Issues Lowest elevation on the island Prone to flooding Valve closed – unused for disposal Did not meet compliance or review boundary rules Bald Head Island Club (Golf Course) requested pond be removed from permit for drainage purposes Village required alternate disposal to meet contractual obligation with developer HRI Basin 3 487,165 GPD HRI Basin 2 181,492 GPD HRI Basin 1 131,343 GPD Original Disposal Capacities
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Phase I - Interim Phase I - Interim - Reshape Basin 1 & 2 (0.4 MGD) - Concurrent with GC Hole Rebuild - Permit Revised to “include” Pond 3 but stipulated must be compliant before activation Provided “Breathing Room” to determine final solution HRI Basin 3 (inactive) HRI Basin 2 75,295 GPD HRI Basin 1 324,705 GPD Modified Disposal Capacities
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Phase II – Final Explore Alternatives for Disposal >0.4 MGD - Initial step: 0.8 MGD build-out reduced to 0.65 MGD - 0.65 MGD Need – 0.4 MGD HRIB = 0.25 MGD deficit Alternatives Considered - Alt. A - Reconfigure/Reshape HRI Basin 3 - Alt. B - Groundwater lowering system for basins 1 & 2 - Alt. C - Convert storm drain pond(s) to HRI basins - Alt. D – Golf Course Reuse
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Alternative A Reconfigure/Reshape HRI Basin 3 Advantages - Meet build-out capacity needs - Maintain current WWTP effluent limits Disadvantages -Require reconfiguration of the golf hole -Easement/Land Acquisition to meet Compliance and Review boundaries -Challenges with freeboard, drainage due to low elevations HRI Basin 3
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Alternative B Groundwater Lowering System HRI Basin 1 & 2 Advantages - Meet build-out utilizing current HRI Basins - Maintain current WWTP effluent limits Disadvantages -Similar to HRI Basin 3 – challenges associated with regulatory requirements compliance & review boundaries -Ponds function as storm drain for the course and island -Easement/Land Acquisition required for boundaries HRI Basin 1 HRI Basin 2
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Alternative C Convert Storm Drain Pond(s) to HRI Basins Advantages - Build-out with additional HRI basin(s) - Maintain current WWTP effluent limits Disadvantages -Significant infrastructure $$ -Impact to golf course -Easement/Land Acquisition -O&M costs long term - Flooding concerns
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Alternative D - Recommended Golf Course Reuse Advantages - Meets build-out needs - Public Acceptance - Desirable by all parties - Utilizes GC Irrigation System Disadvantages - WWTP Effluent Limit Requirements - 5-Day Upset Pond (land intensive) - Wet Weather Storage (land intensive) - Village Water Supply Wells - Club Irrigation Wells
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Proposed Irrigation Areas (Existing GC System) Dedicated Disposal Capacity - 250,000 GPD Reuse Non-Conjunctive - 400,000 GPD HRI Basin Capacity 650,000 GPD Total Disposal Capacity Total Reuse Capacity - 250,000 GPD Non-Conjunctive (Front 9) - 400,000 GPD Conjunctive (Back 9) - Normal Conditions – All effluent to GC Irrigation/Production Well Conflicts Non-Conjunctive Areas Conjunctive Areas HRI Basin 2 HRI Basin 1
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Reclaimed Water Storage Non-Conjunctive Areas Conjunctive Areas HRI Basin 2 HRI Basin 1 GC Irrigation Pond & PS Reuse FM From WWTP Utilize current irrigation pond PS system Unable to comply with DENR Setbacks (property lines, homes, surface waters) House Bill 74 – allowed waivers for setbacks and 0’ setbacks for reclaimed water storage ponds if effluent meets: - 10 mg/l Total Nitrogen - 2 mg/l Total Phosphorous Required plant modifications to meet TN/TP limits: - Mag Hydroxide Chem Feed - Alum Chem Feed - Carbon Source Chem
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5-Day Upset Pond Non-Conjunctive Areas Conjunctive Areas HRI Basin 2 HRI Basin 1 GC Irrigation Pond & PS Reuse FM From WWTP Utilize HRI Basins 1 & 2 for Upset Pond - 1.25 MGD Reqd. (0.25 MGD) - Maintain ambient level in each - Meets required volume Reuse Force Main System Design - Valve/Metered to HRI 1 & 2 - MOV for non-compliant reuse - Controlled by GC Reclaimed Water Meter/Control Valve
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Proposed Project WWTP Improvements Blower Upgrades Magnesium Hydroxide Chemical Feed Aluminum Sulfate Chemical Feed Micro-C Chemical Feed Backup Chlorine Disinfection SCADA/Telemetry Modifications Reuse Transmission System 1,000 LF 10” Reuse Force Main Reuse Meter & Control Valve Vault Meter & Control Valve Vaults HRI Basin 1 & 2 SCADA/Telemetry Additions Anticipated Completion Date May 2016 Village BHI WWTP
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Questions? Contact Information: Tony Boahn, PE tboahn@mckimcreed.com 910.343.1048
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