Frozen Vacuum Sewers and the Lessons from Europe

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Over the Northern winter we read with interest a number of stories related to frozen vacuum systems  which were caused by some of the worst winters seen in 100 years in the North East of America. These stories have increased in recent years with some commentators talking about the reality of climate change and its impact on many types of infrastructure, not just sewerage systems.

To understand some of the problems you need go no further than googling “Plum Island frozen sewers”. The main problems seemed to be related to frozen vacuum valves, water frozen in the pits, gooseneck vents submerged by snow, frozen sewage in the pipework, frozen gate valves and division valves and leaks in the line.

Does this  need to be the case every year that there is a big dump of snow or temperatures fall? Aren’t vacuum system supposed to be resilient?  We don’t have to  look as far afield as the vacuum systems in Alaska or even at the Arctic and Antarctic bases to get some solutions to the problems encountered in America. Germany, France, Poland the UK and some of the Nordic countries like Estonia have experienced very low temperatures and extreme snow falls from time to time with little impact on their vacuum systems.

As an engineering firm we need to be aware of local conditions where ever we install a system whether it is in the arid desert of Australia, tropical conditions in Malaysia, remote islands in the Cocos Islands. All systems should be designed to suit the local conditions..

When dealing in area’s subject to extreme cold we need to take care of how deep the vacuum mains are laid, what type of division valves are used, how the collection pit is designed, where the air intake vent should be for the operation of the valve. Many of these things can be adjusted in existing systems.

One of the important developments in how Flovac vacuum systems are managed is in the use of monitoring systems at the valve and pit. As a standard in cold conditions we monitor the temperature in the pit via our monitoring system.

This would have helped a lot in the Plum island project as any valve failures would have been easily and quickly located due to freezing ensuring no loss of service for residents or sewage overflows into their basements.

The monitoring system also makes it very easy for operators to locate the exact location of collection pits. This is also true in coastal area’s where pits can often be covered by sand during the summer months.

Many communities in the US are fretting over what will happen next winter with their vacuum systems. Will the Fire station chief need to allow residents to use their showers and toilets. Will portable toilets be sold out early, or will everyone just head for Florida.

Maybe one solution is to contact us here at Flovac and we would  bring a team of experts from Europe to look at ways to ensure that your Happy Holiday season is truly Happy.

Flovac Vacuum Sewerage Systems are experts in solving difficult wastewater engineering problems in unique geographic areas with Global Knowledge and Local Solutions.

The Hidden Costs of Gravity Sewers versus Vacuum Sewers

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When looking at what sewage infrastructure to use in a difficult area, most consultants will do a study which compares gravity sewers with vacuum sewer technology. In some smaller communities they may also do a comparison showing a low pressure or grinder pump system.

These costs are usually split between the Capital Cost of the Project and the Whole of Life costs. In some countries the consultant will also do a carbon footprint study to look at the environmental impact of the new infrastructure.

When looking at the Capital Cost for a sewerage infrastructure project engineers look at the following major items.

  • Pump Station Costs
  • Cost of Pipe in the Ground
  • Manholes or collection Pits
  • Property Connection costs to the Collection point
  • Rising Main Cost to the Treatment Plant

Will this information give a municipality or developer the full picture? What is being left off this analysis?

Pump Station Costs   – In a gravity system, multiple gravity pump stations may be required (up to 18) where one vacuum station will handle the flow. Is the cost of the land taken into account? How about the impact of a properties value if situated next to a gravity station?

Pipe Installation Cost – Usually the consultant will look at the price of pipe per metre installed in the ground, but how about how long the construction period is to install pipe in difficult ground where dewatering may be required. The gravity project in the photo  required 2 weeks per every 100 metres of pipe being laid. Some area’s with very hard rock may take longer. If dewatering what is the cost of disposing of the water? If requiring new fill from somewhere else to embed the pipe, what is that cost?

Impact on Community, Trade and House Sales. – If a project takes a long time to be installed then a municipality may not allow a developer to commence the sale of houses until all houses are connected to the sewer. If commercial area’s or shops cannot be accessed for extended periods this may have a financial impact on the project. If homeowners cannot access their homes then what is the political cost?

Easement Requirements – When looking at a low pressure pump scheme where pumps are required on private properties has the cost of an easement been built into the estimate? When looking at Whole of Life costs does it include washing down the sewage off people’s yards after repairs have been made to the pumps?

Treatment Plant Impact  – If designing a gravity sewer where infiltration will need to be accommodated will the Treatment Plant need to be upgraded and what is the impact of the increased  discharge?

Operational Costs and Risks. –  Health and Safety of operators, Odour, gas explosions, fatbergs, wet wipes clogging pumps, exfiltration damage. None of these are adequately covered in assessments.

Energy Costs – Does the community count the cost of the extra energy costs when it is only homeowners paying the cost with grinder pumps or do you need to look at the cost to the town. When infiltration occurs how much extra power will that consume at pump stations and at the treatment plant.

Increased Risk – is there an assessment given over possible EPA or environmental fines if a gravity system or low pressure system discharges sewerage into a sensitive area. What happens in a tourism area if the sewage overflows? How about in a fishery habitat?

There are many other hidden costs and many more long term costs to be taken into account, This is especially true when trying to repair a leak in a pipe 10 metres (30′) under the highway. I am sure you can think of other costs that have impacted on projects you have done in the past, If so, we would love to hear about your experiences.

Marina Port Vell Barcelona installs Flovac System

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On April 27 2015, Flovac commissioned the vacuum system at the Marina Port Vell in Barcelona. Known as one of the finest new marinas for Super yachts in Europe, the owners saw the use of the Flovac system as essential.

The system designed and installed by FLOVAC includes the discharges from buildings in the Marina such as the restaurants, offices, locker rooms, gym, etc … and residences on the boats moored in the Marina.

Wastewater and Bilge Water

The vacuum system has two vacuum networks, one for wastewater generated in the Marina (waste water) and a parallel network where bilge water, which requires pre-treatment to collect the sewage discharged in port .The network of pipes, placed around

the perimeter of the marina, carrying the waste water has vacuum generated by a single vacuum station located in the Marina. It is the single point of electricity needed for the whole system. FLOVAC vacuum valves, which are located in different collection pits are pneumatically operated with this setup, FLOVAC has already installed four vacuum sewerage works in the area of the Port of Barcelona.

No Leaks from the Sewer System can occur

The vacuum system ensures the impossibility of discharges into the sea , is the most economical solution in terms of execution of work, since by its very nature design , the network of pipes need not be buried deep underground and no intermediate pumping.

Moreover, in this case, the system is equipped with a remote control system that allows the owner to know exactly everything that happens anywhere in the sewer.

User Pay for Sewage Discharge

Flovac also designed software to control the discharge of sewage from yachts to the Marina and can accurately invoice by litres of discharge to the sewer. As a result, Marina Port Vell prevents sewage dumped at sea and in return gives them a MARPOL certificate.

MARPOL 73/78 is an international convention for the prevention of pollution at sea. The convention includes regulations aimed at preventing and minimising pollution at sea from ships, and this includes both, accidental pollution and pollution from routine operations.