Another Pumping Station Design Rescue

  • Client: Developer
  • Number of Pumping Stations: 1
  • Project Location: West Midlands
  • System Type: Type 3 Foul Pumping Station

There was no hope Severn Trent Water would consider adopting it.  It fell well short of Sewers for Adoption Guidelines and definitely their addendum.

The multi-million pound housing development in West Midlands was in advanced stages of construction.  An existing private pumping station which was due to be refurbished and submitted for adoption.

When the pumping station was surveyed for suitability for adoption, a whole raft of issues with the system came to light.  Some of which are;

  • Two partly constructed properties were within 8m of the wet well* (See appendix below)
  • Due to the proximity to habitable properties, noise and odour issues were threatening to effect the sale of the neighbouring properties
  • The existing chambers didn’t meet the required emergency storage volume
  • The valve chamber dimensions did not allow for STW valve combinations to be installed
  • The discharge manhole was within the compound with no room for a standard STW flow meter
  • The compound was 25% smaller than the SFA guidelines suggest

 

What Did Paradigm Do?

Paradigm were approached with this issue and being keen to help the developer out, put together a full technical package for the pumping station for submission to STW.  As expected a number of issues were raised and the developer was advised on 4 occasions that in the given circumstances, this pumping station could not be adopted.

Design engineers from Paradigm met with STW’s design team to address the issues to come up with a proposal whereby the system would be adopted, this included;

  • Carrying out a noise and odour report due to the proximity of the properties and executing findings
  • Sourcing a suitable non-mechanical odour control device to be installed on the pumping station vent pipe that could be retro-fitted and is inexpensive to maintain
  • Advising on the upstream drainage network to accommodate the required storage which included adding a new inlet manhole
  • Restructure the valve chamber design to accommodate new a pipework configuration
  • Source an alternative non-intrusive flowmeter that would work with existing STW SCADA software but required less space than a traditional flowmeter
  • Redesigning the compound and hardstanding area including widening the road to allow for tanker access.

Following a number of meetings and conversations, Paradigm worked with STW to arrive at a compliant system which was cost effective for the client and would be adopted once complete.

Ensuring that the pumping station was going to be adopted was key to saving the developer huge sums of money in the ongoing maintenance of the system.

If you have pumping stations that you are struggling to get adopted to technical approved, we’d love to help you out.

 


Appendix

Sewers for Adoption 6th Edition (applicable to some water authorities)

 

2.18.3 – The pumping station should be located no closer than 15 m to habitable buildings in order to minimise the risk of odour, noise and nuisance. Facilities for odour control may need to be installed, depending on the location. The distance is to be measured from the pumping station site boundary (excluding access driveway) to the nearest point on habitable buildings. This dimension may be subject to change depending on the local circumstances and submission of proposals. Preliminary and early discussion with the Undertaker is to be encouraged to ensure agreement of the scheme.

 

Sewers for Adoption 7th Edition (applicable to some water authorities)

D4.1.1 – The minimum distance from the wet well of the pumping station to any habitable buildings should be in accordance with Table D.1, in order to minimise the risk of odour, noise and nuisance. This dimension may be subject to change, depending on the local circumstances and submission of proposals.

Table D.1         Minimum distances of wet wells from habitable buildings

Pump station type Minimum distance (m)
Type 1 5
Type 2 10
Type 3 15

 

D2.2 – Classifications of pumping stations determined by size of peak design incoming flow are listed below:

  • Type 1 – Having an incoming peak design flow of ≤ 0.25 litres per second (typically five dwellings or less);
  • Type 2 – Having an incoming peak design flow of > 0.25 litres per second but less than 1 litre per second (typically six to twenty dwellings);
  • Type 3 – Having an incoming peak design flow of ≥ 1 litre per second (typically more than twenty dwellings) but with per pump rated no more than 30 kW; and
  • Type 4 – Having at least one pump rated more than 30kW (these are outside the scope of ‘Sewers for Adoption’ and guidance should be sought from the Undertaker).

 

Sewers for Scotland 3rd Edition (only applicable to Scotland)

2.24.1.1 – The minimum distance from the wet well hard standing of the pumping station to any habitable buildings shall be in accordance with Table 4, in order to minimise the risk of odour, noise and vibration nuisance. Note: This dimension may be subject to change, depending on the local circumstances and submission of proposals.

Table 4             Minimum Distances of Edge of Wet Well Hard standing from Property Boundary

Pump station type Minimum distance (m)
Type 1 5
Type 2 10
Type 3 15

Pump station types can be identified as below:

  • – Pumping stations shall be classified by incoming peak design flow:
  1. Type 1 – having an incoming peak design flow of ≤ 0.25 litres per second (typically five dwellings or less);
  2. Type 2 – having an incoming peak design flow of > 0.25 litres per second but less than 1 litre per second (typically six to twenty dwellings);
  3. Type 3 – having an incoming peak design flow of ≥ 1 litre per second (typically more than twenty dwellings) but with per pump rated no more than 22 kW each (for 100 A supply).