912f7b27fd4dd9850ac57680e9055699.ppt
- Количество слайдов: 17
Reclaimed Water Solution for Disposal Capacity Village of Bald Head Island 2015 NC AWWA - WEA Annual Conference November 17, 2015
Bald Head Island Brunswick County North Carolina Bladen County Columbus County Brunswick County Pender County New Hanover County Bald Head Island
Bald Head Island
History & Project Drivers v 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 HRI Basin 1 HRI Basin 2 HRI Basin 3 WWTP
History & Project Drivers v. Utility Ownership Transferred to Village of Bald Head Island - Transfer occurred late 90’s - Contractual obligation - island build-out capacity HRI Basin 1 HRI Basin 2 HRI Basin 3 WWTP
HRI Basin 3 Issues v. Lowest elevation on the island v. Prone to flooding v. Valve closed – unused for disposal v. Did not meet compliance or review boundary rules HRI Basin 1 131, 343 GPD HRI Basin 2 181, 492 GPD HRI Basin 3 487, 165 GPD Original Disposal Capacities v. Bald Head Island Club (Golf Course) requested pond be removed from permit for drainage purposes v. Village required alternate disposal to meet contractual obligation with developer
Phase I - Interim HRI Basin 1 324, 705 GPD v. Phase I - Interim HRI Basin 2 75, 295 GPD HRI Basin 3 (inactive) Modified Disposal Capacities - 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 v. Provided “Breathing Room” to determine final solution
Phase II – Final v. 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 v. 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
Alternative A Reconfigure/Reshape HRI Basin 3 v Advantages - Meet build-out capacity needs - Maintain current WWTP effluent limits v 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
Alternative B Groundwater Lowering System HRI Basin 1 & 2 v Advantages - Meet build-out utilizing current HRI Basins - Maintain current WWTP effluent limits v 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
Alternative C Convert Storm Drain Pond(s) to HRI Basins v Advantages - Build-out with additional HRI basin(s) - Maintain current WWTP effluent limits v Disadvantages - Significant infrastructure $$ - Impact to golf course - Easement/Land Acquisition - O&M costs long term - Flooding concerns
Alternative D - Recommended Golf Course Reuse v Advantages - Meets build-out needs - Public Acceptance - Desirable by all parties - Utilizes GC Irrigation System v Disadvantages - WWTP Effluent Limit Requirements - 5 -Day Upset Pond (land intensive) - Wet Weather Storage (land intensive) - Village Water Supply Wells - Club Irrigation Wells
Proposed Irrigation Areas (Existing GC System) v Dedicated Disposal Capacity - 250, 000 GPD Reuse Non-Conjunctive - 400, 000 GPD HRI Basin Capacity 650, 000 GPD Total Disposal Capacity v Total Reuse Capacity - 250, 000 GPD Non-Conjunctive (Front 9) - 400, 000 GPD Conjunctive (Back 9) - Normal Conditions – All effluent to GC HRI Basin 1 HRI Basin 2 Non-Conjunctive Areas v Irrigation/Production Well Conflicts
Reclaimed Water Storage v Utilize current irrigation pond PS system v Unable to comply with DENR Setbacks (property lines, homes, surface waters) v House Bill 74 – allowed waivers for setbacks and 0’ setbacks for reclaimed HRI Basin 1 water storage ponds if effluent meets: HRI Basin 2 - 10 mg/l Total Nitrogen - 2 mg/l Total Phosphorous GC Irrigation Pond & PS Reuse FM From WWTP Non-Conjunctive Areas v Required plant modifications to meet TN/TP limits: - Mag Hydroxide Chem Feed - Alum Chem Feed - Carbon Source Chem
5 -Day Upset Pond v Utilize HRI Basins 1 & 2 for Upset Pond - 1. 25 MGD Reqd. (0. 25 MGD) - Maintain ambient level in each - Meets required volume v Reuse Force Main System Design - Valve/Metered to HRI 1 & 2 - MOV for non-compliant reuse - Controlled by GC HRI Basin 1 HRI Basin 2 GC Irrigation Pond & PS Non-Conjunctive Areas Reuse FM From WWTP Reclaimed Water Meter/Control Valve
Proposed Project v. WWTP Improvements ü ü ü Blower Upgrades Magnesium Hydroxide Chemical Feed Aluminum Sulfate Chemical Feed Micro-C Chemical Feed Backup Chlorine Disinfection SCADA/Telemetry Modifications Village BHI WWTP v. Reuse Transmission System ü 1, 000 LF 10” Reuse Force Main ü Reuse Meter & Control Valve Vault ü Meter & Control Valve Vaults HRI Basin 1 & 2 ü SCADA/Telemetry Additions v. Anticipated Completion Date May 2016
Questions? Contact Information: Tony Boahn, PE tboahn@mckimcreed. com 910. 343. 1048