water services national training group and national federation of group water schemes 7 th annual...
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Water Services National Training Group and
National Federation of Group Water Schemes
7th Annual Rural Water Services Conference
18th September 2008
“Septic Tank Effluent Drainage System”
STEDS (Update)
Jim McGuireSenior Engineer
North Tipperary County Council
Background
Project description
Current status
Experience /Identified Issues
The Challenge:
Sustainability
Ease of Maintenance
Robust performance
Process performance
Low energy costs
Low operating costs
Alternative wastewater treatment systems
for small rural communities
Approach
Literature search
Short list of options
Real life applications
Pilot Project
PROJECT TEAM
Treatment System: Orenco, USA
Consulting Engineers: Nicholas ODwyer &Partners
Contractor: EPS, Mallow, Co. Cork
Client: North Tiperary County Council
Water Services National Training Group
Funding providing by: Department of Environment ,
Heritage and Local Government
Fibreglass Tank in each Garden
Primary treatment in interceptor tanks
1000- or 1500-gallon tank per residence
70% removal of fats, oils, and greases
24-hour emergency storage
12-year pumpout with 95% confidence
Abuses stay in interceptor tank
Chemical sources easier to identify
STEDS Components
• Pump vault
• High-head effluent pump
• Filter cartridge
• Float assembly
• Discharge assembly
Components, cont.
Collection System
Shallow burial depth
Laid to contour of land
No minimum velocities
No oversized designs
Low operation and maintenance costs
Secondary Treatment
Packed bed filter
Engineered textile material
Complete, premanufactured package
Operates in an unsaturated condition (not submerged)
Uses filtration and biological/chemical reduction
Flexible in design Adaptable to varying site conditions Allows for phased development, modular Can be integrated into existing sewer infrastructure? Can be integrated into existing treatment system
Design includes storage/reserve in the event of power outages or need to repair mainline break
Low-impact construction Minimal disruption to community
Advantages
Advantages
Cost-effectiveness
Low initial costs?
No manholes
No pumping stations
Low operating costs
Low maintenance costs
Low and gradual repair/replacement costs
Benefits
May allow the construction of houses in areas where standard sewers or septic tank systems cannot be used
Has affordable installation costs and low maintenance costs
Has little visual impact
1. Retrofit Challenge
• No rain water can enter system
• No ground water can enter system
Experience
Experience
2. Sampling Challenge
• Low flows pose particular challenges
• Various arrangements tried
Householders Play an Important Role
3. Householders Role
• No bleaches
• No discharges from water softeners
• No under sink macerators
• Minimise phosphates in detergents
Experience
COSTS
29 Houses served
Cost outturn not finalised (€850,000 excl. VAT)
Includes range of non typical items
Overseas manufacture / Shipping
Retrofit project
Reconfiguration of existing connections
Ground conditions
Telemetry/data capture
Sampling/monitoring
Additional connections
Additional single unit treatment system
Non typical costs
The Challenge:
Sustainability
Ease of Maintenance
Robust performance
Process performance
Low energy costs
Low operating costs
Alternative wastewater treatment systems
for small rural communities
• Retrofit/rainwater challenges overcome• Sampling challenges resolved• Operating procedures improved
• Final judgement awaited• Further Close monitoring• Performance is positive• Phosphates
Conclusions
End
Water Services National Training Group and
National Federation of Group Water Schemes
7th Annual Rural Water Services Conference
18th September 2008