DESIGN

Our systems are designed following guidelines that are set out and established on a national and international level. These include writings by WRC, British Water, BS and BS EN standards amongst others. We follow three main guideline steps in our design to ensure each system is Fit for Purpose and Built to Last.

PIPELINE VELOCITIES

To ensure stability within the pipelines and to keep them from of blockages we stick to we ensure that the speed of the flow through the piplines is kept within strict parameters. To avoid any potential blocking of a rising main by a built up of silt the flow must go through the rising main at a minimum rate of 0.75m/sec, equivalent to 1.67mph, about walking pace. In order to avoid excessive wear of a rising main and to maintain the flow without using over-powerful pumps, an upper limit of 1.8m/s, equivalent to 4.0mph, is used. This is a good jogging speed. In some circumstances speeds of up to 3.0m/s are used without compromising on good design which is the maximum we will go before the chance of long term damage comes into play.

EMERGENCY STORAGE CAPACITY

In the case of catastrophic failure of a pump station where there is no longer any ability to discharge the wastewater, what happens? In the case of a private pump station a period of 24 hours must be available in order for an engineer to attend site and rectify the issue. For an adopted system, some water authorities may reduce this requirement to 4 hours where they have the capabilities to service these requirements. Unfortunately, how these volumes are calculated vary dramatically. For an adopted pump station the emergency storage per house varies from 62 litres to over 600 litres. With private pumping systems several methods are used such as British Flows and Loads 4, Plumbing Services Design Guide, Loading Units to BS EN 12056-2:2000, BS EN 752:2017 among other guidance.

RETENTION TIMES AND SEPTICITY

Although the calculation of retention times and septicity is only required for adoptable pump stations for the water authorities approval, we have chosen to use it to ensure all foul water pump stations are at a minimum risk of creating dangerous gases or causing a smell. Retention time is how long sewage will be sitting around for; within the rising main and in the the wet well. Sewage sitting around too long can cause septicity, where the sewage starts to break down. When this happens dangerous gases such as hydrogen sulphide can be formed creating a dangerous atmosphere and methane which can cause the system to smell. This calculation does not apply to surface water.

SOME OF THE GUIDANCE USED IN OUR DESIGNS

Paradigm Systems cannot be held responsible for the content of other websites.

Please note, this is for guidance only and is exhaustive.

Sewers For Adoption 6th Edition (SfA6), published by the Water Research Centre (WRc plc)

More details can be found here http://sfa.wrcplc.co.uk/sewers-for-adoption-6th-edition.aspx

More details about the Water Research Centre can be found here http://www.wrcplc.co.uk/

Sewers For Adoption 7th Edition (SfA7), published by the Water Research Centre (WRc plc)

More details can be found here http://sfa.wrcplc.co.uk/home.aspx

More details about the Water Research Centre can be found here http://www.wrcplc.co.uk/

Sewers For Adoption 8th Edition (SfA8)

Design and Construction Guidance (DCG) for foul and surface water sewers offered for adoption under the Code for adoption agreements for water and sewerage companies operating wholly or mainly in England draft 14/02/2019, published by Water UK

More details can be found here https://www.water.org.uk/sewerage-sector-guidance-approved-documents/

More details can be found about Water UK here https://www.water.org.uk/

The SuDS Manual (C753), published by the Construction Industry Research and Information Association (CIRIA)

More details can be found here https://www.ciria.org/Memberships/The_SuDs_Manual_C753_Chapters.aspx

More details can be found about the Construction Industry Research and Information Association (CIRIA) here https://www.ciria.org/

Codes for Adoption (CfA), published by Water UK

More details can be found here https://www.water.org.uk/technical-guidance/developers-services/codes-for-adoption/

And https://www.ofwat.gov.uk/regulated-companies/markets/connections-market/code-adoption-agreements/

Code Of Practise - Flows And Loads 4 (On Sizing Criteria, Treatment Capacity For Small Wastewater Treatment Systems), published by British Water

More details can be found here https://www.britishwater.co.uk/code-of-practise-flows-and-loads-4-on-sizing-criteria-treatm.aspx

More details can be found about British Water can be found here https://www.britishwater.co.uk/

Plumbing Engineering Services Design Guide, published by the Chartered Institute of Plumbing and Heating Engineering (CIPHE)

More details can be found here https://www.ciphe.org.uk/professional-members/publications/plumbing-engineering-services-design-guide/

More details can be found about Chartered Institute of Plumbing and Heating Engineering (CIPHE) can be found here https://www.ciphe.org.uk/

BS EN 12056-2:2000 - Gravity drainage systems inside buildings. Sanitary pipework, layout and calculation, published by the BSI Group

More details can be found here https://shop.bsigroup.com/ProductDetail/?pid=000000000030007203

More details can be found about the BSI Group can be found here https://www.bsigroup.com/

BS EN 752:2017 - Drain and sewer systems outside buildings. Sewer system management, published by the BSI Group

More details can be found here https://shop.bsigroup.com/ProductDetail?pid=000000000030404653

More details can be found about the BSI Group can be found here https://www.bsigroup.com/

Water Industry Mechanical & Electrical Specifications (WIMES), published by the Pump Centre.

More details can be found here https://www.pumpcentre.com/SitePages/WIMES.aspx

More details can be found about the Pump Centre here https://www.pumpcentre.com/

WIS 4-04-02 December 2012 - Specification for package pumping stations intended to serve more than one property, published by Water UK

More details can be found on this here https://www.water.org.uk/wp-content/uploads/2018/11/wis-4-04-02-final-december-2012.pdf