vacuum sewers for coastal areas
DESCRIPTION
What are vacuum sewers and how do we install such a system in coastal areasTRANSCRIPT
Vacuum Sewers – A Viable Alternative for Coastal Areas
Soma Bhadra, PE www.consult-proteus.com
Denny Moss www.airvac.com
Conference on Coastal Engineering Practice 2011 San Diego, CA
Monday August 22, 2011
Why Vacuum Sewers?
Uses Differential Air Pressure
to Move Wastewater
When Gravity
Sewers have Constraints
Environmentally Sensitive Areas
Tight Working Areas
High Groundwater
Rock
Flat Rolling Terrain
Unstable Soil
Vacuum Sewers
• Small pipe sizes (4 to 10-inches)
• No manholes and cleanouts
• Shallow depths (3 – 5 feet)
• High Scouring velocities (8 – 18 fps)
• No exposure to sewer gas
• No I/I, Exfiltration prevented
Benefits
• Reduces costs
• Lines stay clean
• Reduce environmental impact
• Very low odor problems
• Leaks cannot go un-noticed
• Safe
4
Home Valve Pit Vacuum Sewer
Vacuum Station
Force main
How Vacuum Sewer Works
Home to Valve Pit
Air Intake
• Pit /Sump & Cone
• Vacuum Valve
• Sump Breather Unit
• Anti-flotation Collar
The Valve Pit
Vacuum System Layout
Design Guide
D Design Max Design Max (in) (gpm) (gpm) (# homes) (# homes) 4 40 55 60 85 6 105 150 165 235 8 210 305 330 470
10 375 545 585 850
Pit Type Peak (gpm) Maximum Peak (gpm)
Standard 0.5 - 1.5 3
Single Buffer
3.1 - 15 30
Dual Buffer 15 - 30 60
Oak Island, North Carolina
81+miles of vacuum sewers
9 vacuum stations
4,500gpm pump station
10+ miles wastewater + reuse force main
400,000 gpd MBR WWTP
Service Areas and Vacuum Stations
9 Service areas, 1 Vacuum Station in each, 1 central Pump Station
Failing Septic System
Beach properties,
vacation rentals
Very flat High groundwater
Intracoastal Waterway
Hurricane prone
Wetlands + Environmenta
lly sensitive
12
Home Valve Pit Vacuum Sewer
Vacuum Station
Force main
How Vacuum Sewer Works
Collection System Design
SDR 21, Schedule 40 PVC fittings
O-Ring, Rieber gasket
20 – 500 ft. at 0.2% Slope with 1 to 1.5ft lifts
18’ total available lift at 16” Hg, 5’ used to evacuate the sump’ 13’ available for sewage transport
Collection System
Vacuum Station
Incoming Vacuum Mains
Vacuum Pumps Collection Tank Sewage Pumps
Force Main
Standby Generator
Odor Control
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Vacuum Sewers – A Viable Alternative for Coastal Areas
Acknowledgement: Town of Oak Island, North Carolina Black & Veatch, Cary, NC
Soma Bhadra, PE (858) 353-2805 [email protected] www.consult-proteus.com Denny Moss (800) 247-8229, ext. 229 [email protected] www.airvac.com