13th September 2006Cavan Crystal Hotel, Cavan

Rural Water Services Conference

Single House Treatment Systems

Matt ShorttDirector of Services

North Tipperary County Council

Introduction

1. Issues for the provision of wastewater facilities for small rural communities

2. Seven Villages Pilot Project

3. STEDS Pilot Project

Single Rural Dwellings

Settlement Plans

Package Plants

Maintenance Contracts

Settlement Plans

Issues

Capital Cost/Unit Cost

Annual Operating Cost

Community support

Appropriate Treatment

Future growth

Issues contd.

DesignReceiving waters/groundUnderloadingFuture growth prediction

CapitalSewers/NetworkPlant

Operation SludgeGrit/screeningsFats Oils and GreasesUser behaviour

Minimise cost (capital and operating)Facilitate innovation based on proven technologyScaleRuralProximityGeographical SpreadInclude networkRange of ground conditions and discharges pointsOther services

7 Villages Pilot - Objectives

7 villages - DBO

Requirements

Construction of new wastewater collection network in 7 villages

Connection of wastewater collection network to individual septic tanks / waste pipes

Construction of 7 new small scale wastewater treatment works and outfall pipelines

Operation and maintenance of wastewater collection networks and treatment plants for a period of 20 years following completion

Compliance with requirements of sludge management plans

Successful Tender

5 No. Gravity Collection Systems, 2 No. Vacuum Systems.

Concrete cast in-situ conventional Activated Sludge Plant at all 7 Villages (Concentric).

Screening and Compaction at all 7 Sites.

Sludge Holding Tank at all Sites.

Generator at all 7 WWTW’s.

2 No. Administration Buildings

Standard Landscape details.

Contd.

Costs include O+M of sewers and treatment plant.

Fixed and variable payments.

Variable payments dependent on load.

Capital replacement fund to ensure values of asset maintained.

Rate provided for future connections.

Sludge Storage and Transfer included.

Unit Costs

Village Existing Equiv No

Connections Unit cost

Upperchurch 45 €25,093

Loughmore 48 €22,557

Clonmore 45 €31,739

Terryglass 80 €20,277

Clonoulty 60 €25,705

Hollyford 65 €23,725

Cullen 45 €22,973

  Average €24,176

O/heads €4,715

Total €28,891

Is the technology appropriate?

By how much will the unit costs reduce?

What is an economic cost?

How will it be funded (Developer + DEHLG + LA)?

Will development follow?

Questions

“Sustainable Technologies for Small Wastewater Treatment Works”

WRc Collaborative ProjectWater Research Centre

Search for and review alternative technologies

Sustainability Maintenance Risk of failure Process performance Low energy costs Low operating costs Renewable energy options

Approach

Literature search

Short list

Real life applications

Evaluate whole life costs

Alternative collection systems

Vacuum

Pressure

Gravity

Alternative treatment systems

Lagoons or ponds

Biological filtration systems

Mechanical systems

Combinations of each

Septic Tank Effluent Drainage System

STEDS

Effluent vs Gravity Sewer

Two Possibilities

Septic Tank Effluent PumpingSeptic Tank Effluent Gravity

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

Effluent Sewer ComponentsFiberglass Reinforced Tanks

Pump vault

High-head effluent pump

Filter cartridge

Float assembly

Discharge assembly

Splice box

Components, cont.

Collection System

Shallow burial depth

Laid to contour of land

No minimum velocities

No oversized designs

Low operation and maintenance costs

Odour control necessary in certain applications

Secondary Treatment

Packed Bed Filter - Attached Growth Process

Highly stable, reliable

Uses fixed film media

Operates in an unsaturated condition (not submerged)

Employs intermittent dosing

Uses filtration and biological/chemical reduction

Secondary Treatment

Packed bed filter

Engineered textile material

Appropriate tankage and timed dosing

Complete, premanufactured package

Flexible in design Adaptable to varying site conditions Allows for phased buildout Can be integrated into existing sewer

infrastructure

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

Allows the construction of houses in areas where standard sewers or septic systems can’t be used

Has affordable installation costs and low maintenance costs

Has little visual impact

Householders Play an Important Role

13th September 2006Cavan Crystal Hotel, Cavan

Rural Water Services Conference