Slide 1

Anne Arundel County Department of Public Works Mayo Water Reclamation Facility Presented to West/Rhode River Keepers March 23, 2012 Slide 2 Agenda Project Purpose and Need Statement Plant Service Area Septic Tank Effluent Pump (STEP) System Flows Treatment Facilities Unit Processes Performance Plant Outfall Operating Costs Refurbish Existing Units Plant Expansion Efforts Design of Conventional Plant Negotiations with MDE and FDA Expansion Alternatives Ongoing Plant Improvements Phase 1 Improvements Current Options Being Considered Slide 3 Project Purpose and Need Expand Capacity Lift Moratorium Current Permitted Capacity 0.615 mgd Current Allocated Flow 0.579 mgd Ultimate Projected Flow 1.14 mgd Upgrade Treatment Enhanced Nutrient Removal (ENR) Current Total Nitrogen 18.6 mg/l Current Total Phosphorous 0.76 mg/l ENR-Total Nitrogen 3 mg/l ENR Total Phosphorous 0.3 mg/l Slide 4 Service Area Need service area figure from George Septic tank effluent flows to pumping stations Flow pumped to treatment plant Solids Handling Slide 5 Flows Current Average Daily Flow (ADF) = 0.56 mgd Peak Flow = 2.18 mgd Currently 3,615 EDUs Projected Build-out ADF = 1.14 mgd (uses 225 gallons per day per EDU) Build-out Peak = 3.58 mgd (uses MD peaking curve) Essentially Un-changed since Mayo inception Service Area continued Build-out Equivalent Dwelling Units (EDUs) Slide 6 Treatment Facilities Treatment Train STEP solids settle Influent Pumping Recirculating Sand Filters Reduces solids (TSS), ammonia-N (NH3), Biological Oxygen Demand (BOD) Small degree of pathogen reduction Emergent Wetlands Subsurface flow lined gravel beds supporting growth of bulrushes and cattails Further reduces solids, (TSS), ammonia- N (NH3), Biological Oxygen Demand (BOD) Small degree of pathogen reduction Phosphorus Clarifier Lime added to precipitate phosphorus Slide 7 Treatment Facilities Treatment Train, continued Peat Wetlands Drained, lined beds, with alternating layers of sand and peat with a grassy vegetative cover over which wastewater is sprayed Effluent polishing (TSS removal) Some pathogen reduction UV Disinfection Primary source of pathogen reduction UV radiation penetrates pathogen DNA and precludes them from reproducing Effluent Pumping Slide 8 RHODE RIVER OFFSHORE WETLANDS EFFLUENT PUMPING STATION EFFLUENT UV DISINFECTION PEAT WETLANDS RAPID MIX CHEMICAL CLARIFIERS DISTRIBUTION BOX A MAIN INFLUENT PS RECIRCULATING SAND FILTERS EMERGENT WETLANDS INFLUENT SLUDGE STORAGE INFLUENT PEAT WETLAND PS FILTER PS FILTER PS 24 HOUR EMERGENCY SHELLFISH STORAGE / FLOW EQUALIZATION TANKS 2 HOUR EMERGENCY SHELLFISH STORAGE PEAT WETLAND UV DISINFECTION Existing Mayo WRF Slide 9 Operating Performance Annual Averages: 2011 Total Suspended Solids 2.0 mg/l Total Nitrogen 18.6 mg/l Total Phosphorus 0.76 mg/l Fecal Coliform