pressurized sewer systems An introduction to E/One LPGP ROTORUA - - PDF document

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An introduction to E/One pressurized sewer systems LPGP

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What we will cover today

• Pressure Sewer in Rotorua
• What is a Pressure Sewer System (LPGP) ?
• How does it work ?
• Reticulation system components
• Homeowner Information

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Introduction

• Rotorua District Council has committed to the implementation
• f sewerage schemes to service fourteen lakeside

communities within the District.

• These communities are situated along four major lakes in

Rotorua that are well known for trout fishing and other recreational uses.

• The implementation of a sewerage scheme in these

communities is one of the measures being put in place to improve water quality within these lakes.

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Challenges faced by RDC with conventional gravity system

a. The need for trench dewatering

• Pumice soil type

made it impossible to dig and lay the pipelines in dry trench.

• Dewatering operation

undertaken 24 hrs before excavation.

• Dewatering

undertaken continuously until the pipeline has been laid and backfilled.

• Added cost to

projects.

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Challenges cont’

b. Difficult Site Access to Lakeside Properties & Reinstatement Issues

• Undermined

established driveways, plants and landscaping.

• Created a “war zone”

like setting.

• Reinstatement

expectations between the affected property

• wner and Council.
• Added cost to project.

Typical level of property disruption resulting from pipeline construction along lakeside properties

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What is pressurised sewer?

• Sewage reticulation network
• Each property has a tank and grinder pump
• Macerated slurry is pumped through small bore PE pipes
• Pipes can follow the contours of the land (no deep trenching)
• Capable of pumping many km’s to centralized WWTP or

manhole

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What is pressurized Sewer?

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Origins of pressurized sewer

• The pressure sewer concept proposed by Harvard Engineering,

Professor Gordon M. Fair in 1965

• The ASCE commissioned Paul Farrell to implement a full- scale

“Demonstration Project” in Albany NY

• Applying GE’s food waste disposal and home wastewater treatment

systems technology the team developed the pump unit to be used.

• For 13 months they studied 12 working units and recorded the

environmental, electrical and mechanical performance of the project.

• A GE management buyout of the technology formed the first

pressure sewer company - Environment One Corporation

• EOne now has more than 350,000 units in operation in more than 10

countries

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What are the advantages?

• Not subject to stormwater or groundwater infiltration
• Suitable for sites with no natural fall where gravity

system would require many pumping stations

• And sites with high water tables
• Lower cost of reticulation - lower material, excavation,

dewatering and reinstatement costs

• Minimal disruption to existing infrastructure

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What are the advantages?

• Extended power blackouts less likely to lead to overflows

than conventional PS, (over 24hrs storage at each home)

• Lower treatment plant operational costs due to substantially

lower inflow. New plants can be designed smaller

• More consistent inflow to treatment plant due to buffering

effect of the tanks

• Staged build out advantages reducing up front capital costs

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How does it work?

• The E/One pump is a semi Progressive Cavity pump

based on the Moineau principle

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Reticulation System

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Home owner info

• What equipment do I have on my property ?
• What disruptions can I expect ?
• What about noise / smells
• What can / can not go through the system ?
• What happens if the alarm goes off ?

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Equipment on site

Pump Station Alarm Panel

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Equipment on site

Pump Station Alarm Panel

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Disruptions – Street Mains

Either directional drilled or shallow open cut.

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Disruptions – Home owners

Access to electrical distribution board & Wiring of alarm panel

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Disruptions – Home owners

Installation of pump station

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Completed Installation

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Operation & Maintenance

• The E/one grinder pump is designed as any other home appliance,

that is run to failure.

• There is no requirement for annual preventative maintenance
• After 37 years of experience e/one have sufficient operating data

which states an average mean time between service calls of 10 years.

• Actual pump life exceeds 25 years
• Average maintenance cost is about $85 / pump / year
• Low Energy Consumption - Pump is activated automatically. Runs

for short periods. Typical annual energy consumption is approximately $25 / year.

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Do’s and Don’ts

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If the Alarm goes off ?

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