01299 823158

Drainage Assessment & Maintenance

Sandfield Penstock Solutions provide drainage assessment and maintenance services to support you to fully understand how your drainage system is intended to work and to ensure that it is operating effectively.

Drainage Assessment and Maintenance

Penstock Solutions provide drainage investigations and maintenance services to support you to fully understand how your drainage system is intended to work and to ensure that it is operating effectively.

Understanding how liquids flow from your business is essential if you are looking to develop effective pollution containment processes and systems. Penstock Solutions approach to water pollution containment identifies your drainage system as the principal pathway of liquids leaving your site to the environment and the best opportunity to contain pollutant materials.

Understanding your sites’ pathways to the environment with clear and accurate drainage documentation, including 3D drainage plans, is the key to mitigating and in the worst case defending a pollution release. Sandfield Penstock Solutions provide accurate drainage plans that allow you to monitor your drainage systems to maintain efficient operation and significantly save time and money by avoiding emergency drainage repairs.

Why would you need a drainage system assessment?

Penstock Solutions provide drainage investigations either to evidence that drainage networks will be effective in the event of a pollution event or as part of a defence following a pollution release.

A well maintained, fully functioning drainage system is the cornerstone of the pollution containment systems that Penstock Solutions provide. 

Drainage systems are designed to effectively and efficiently remove liquids from a site and provide the best option for containing pollutant materials if you are to suffer a pollution event. A poorly maintained drainage network will have a significantly negative impact on your ability to contain pollutant materials in the event of a spill, fire or flood.

Some of the most common faults that our drainage network investigations identify and resolve include:

  • Misconnections, ie. mis-directing foul or polluted water into the surface water run off pathways or directing commercial use run off into the surface water run off
  • Benching Failure, ie. manhole chamber structures eroding causing run off to seap into ground water or polluted ground water to enter your drainage network
  • Damaged Pipes, ie. underground pipes leaking.
  • Equipment Failure, ie. Oil Separators not connected to alarms or not maintained and filling with silt.
  • Understanding Run Off Pathways, ie. failure to understand the final destination of your drainage pathways.


Drainage Systems Investigation – Case Study

A large shopping centre contacted Sandfield Penstock Solutions as they were being blamed for flooding on a neighbouring golf course. 

Our investigation team quickly identified that the centres attenuation pond was being flooded with tidal water. The water level was filling to capacity at high tide, resulting in the attenuation pond permanently being flooded. On further investigation our team discovered that the non-return valves implemented to allow rain water to leave the site but prevent tidal water entering the attenuation pond were seized in the open position. This had caused a significant silt build up within the drainage run offs reducing the capacity of the attenuation pond, limiting flow run off and preventing the pond from maintaining its design levels.

The non-return valves were serviced by the team at Penstock Solutions and immediately after the next low tide water levels dropped by more than 300mm.

The drainage system investigation quickly identified the issue and enabled Sandfield Penstock Solutions to implement a simple, cost and time effective fix, satisfying the client and their understandably unhappy neighbour. 

How does the Penstock Solutions drainage investigation service work?

1. Understanding your drainage pathways.

The first step in a drainage network investigation is to identify the different types of drainage and how they are designed to work.

Drainage networks typically have up to four drainage pathways including:

  1. Surface Water (SW)
  2. Foul Water (FW)
  3. Combined Water (CW)
  4. Above Ground Pathways

Surface Water Pathways (SW)

Surface Water pathways (SW) are designed to manage and direct rainfall offsite to the environment. 

Surface Water networks cannot be used for any commercial water activity unless it has been processed correctly and permitted by the regulator. If you allow anything other than rainwater or permitted water to use the Surface Water Drainage pathway that constitutes a pollution event. Activities that could be considered commercial include tasks as innocent as washing out the bins, cleaning company cars, hosing down the yard or emptying mop buckets down the drain. 

During a spill fire or flood, you need to be able to prevent surface water flow reaching the enviroment. If polluted surface water run off leaves your site that constitutes a pollution event with  the potential of fines or criminal action against the polluter.

Foul Water Run Off Pathways (FW)

Foul Water run off pathways (FW) are used exclusively to take dirty or processed water away; this includes all liquids from toilets, washrooms and commercial activity under consent. It is important to avoid surface water run off entering the foul water network as this will significantly reduce the capacity of the utilities system. 

For sites discharging commercial wastewater a consent permit is normally issued by the water utility company. If a foul water pathway is polluted beyond consent levels the water company have the power to issue fines and charges to address any damage caused. It is also possible that spills or firewater runoff can be rejected and discharged into the environment via a combined sewer overflow (CSO). This also constitutes a pollution event and will result in fines and possible criminal action being taken against the polluter by the regulator. 

Combined Water Run Off Pathways (CW)

In built up areas where it is impossible to create separate surface water and foul water pathways combined foul and surface water sewers are necessary. Allowing polluted materials from firewater run off, spillages or floods to enter combined water run off pathway can also result in action from the water company and the environmental regulator.

Above Ground Pathways

In many businesses there is no drainage system with rainwater flowing directly onto permeable ground or  channelling to a ditch. This flow is impossible to manage and is not recommended for any activity that poses a water pollution risk.

2. Drainage Asset Assessment 

Sandfield Penstock Solutions identify and inventory the features, devices and equipment on your drainage network that require maintenance including:

  • Pollution Containment Devices
  • Oil Separators
  • Flow Control Devices
  • Catch Pits
  • Siphonic Drainage
  • Attenuation Ponds
  • Flood Controls
  • Soakaways 

If your site has a high level of vehicle activity this will cause increased levels of hydrocarbon and silt build up in your drainage network and devices. Drainage pathways run to a variety of receptors, if these receptors are not maintained regularly they quickly lose their effectiveness and increase the flow of pollutant materials from your business to the environment.

3. Drainage Improvement Recommendations

The outcome of the Drainage Investigations is to identify issues and make recommendations to resolve these issues. This includes repairs and maintenance on existing systems where possible and replacement of systems and devices where upgrades are available or required.

The findings and recommendations of the drainage network investigation are then presented to the customer and all relevant stakeholders so they can clearly see the issues and solutions for themselves, empowering them to make informed decisions about the investment required to address those issues. 

The drainage systems investigations provided by Penstock Solutions have saved our customers significant amounts of money and disruption by quickly identifying issues and implementing simple, cost and time effective solutions.

If spill containment and CIRIA c736 compliance is currently a consideration for you please do not hesitate to call 01299 823158 or email us, we will be very happy to discuss our solutions with you.


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