Types of Pump Stations for Housing Developments
In order for a housing development to connect to the Irish Water Network to avail of wastewater services, there are codes of practice and standard details that must be followed. These codes and standards relate to the wastewater infrastructure within the development such as pipework, drains, manholes, inspection chambers, storage facilities and pump stations. They are important because they are based on best practice and the experience of local authorities in the provision of wastewater services. The same codes and standards also apply to commercial developments. In this article, we focus on pump stations for housing developments and some of the relevant codes and standards. For a proposed housing development, the site engineer will determine the appropriate requirements for a pump station. He/she will then supply these specifications to a reputable wastewater treatment company in order to provide a suitable pump station.
The table below lists the type of pump stations for housing developments to which the codes and standards refer:
|Type||Size||No. of Dwellings||Incoming Peak Design Flow|
|1||Small||5 or less||0.25 litre/second|
|2||Mid-range||6 to 20||0.25 – 1 l/s|
|3||Medium||>20||> 1 l/s|
Note: Higher capacity pumping stations are not detailed in the codes and standards but still require the specific approval of Irish Water.
Housing Development Pump Station Cost
Pump stations for housing developments need to be cost effective and must be shown to cost less than a conventional gravity system in a net present value (NPV) assessment over 40 years. Not all new housing developments will require a pump station as a part of the sewerage works but in some instances, due to the topography of the area served, it is a necessity. If this is the case, the developer needs to provide evidence that the physical conditions of the site do not allow for full gravity works.
Impact on Existing Works, Emergency Storage and Overflow
When proposing and designing pump stations for housing developments, the impact on existing wastewater works in the area needs to be taken into consideration. It’s important that the action of the pump station does not compromise the capacity of the existing water network. Irish Water may request the provision of storage facilities at the pumping station to limit the effluent discharge into the public sewerage network.
In the event of flooding during pump or power failure, any resulting overflows have the potential to negatively affect the environment and must be minimized. Any provisions for emergency overflow situations must first be made in agreement with Irish Water and the EPA (Environmental Protection Agency) as part of the design proposal.
Pump Station Operation
A pump station for a housing development must have 100% standby capacity. This means it must have at least two or more submersible pumps on a duty/standby or duty/assist/standby arrangement. Provision for remote monitoring by telemetry should be made in order to transfer data to the Irish Water Control Centre. The system must have the capacity to detect alarm conditions and inform the appropriate parties.
The collection of data must include the following information:
- Available/Run/Trip status for all pumps
- Status for all float switches
- Sump level
- Instantaneous flow
- Totalised flow
- Mains Power Failure
- UPS Fault/Healthy Status
Installation Works and Testing
During the construction of the pump station, field engineers for Irish Water will carry out site inspections. Onsite staff must keep a quality assurance folder containing the appropriate documentation relating to the installation. After the completion of installation works for any housing development pump station, Irish Water require proof that it is fit for purpose prior to any official use. A document package must be provided to Irish Water personnel prior to commissioning of the pump station. This package must include:
- operation and maintenance manuals
- as constructed drawings
- control panel wiring diagrams
- warranty documentation
- full pump details including performance curves and power ratings
This article simply gives an overview of some of the main codes and standards for housing development pump stations required by Irish Water. The site engineer will ensure that the standards are met by providing the design specifications to the pump station suppliers who take care of the rest. The process of connecting to the water network has been made simple by Irish Water, simply visit https://www.water.ie/connections/get-connected/housing-development.xml to begin. The best time to start an application is prior to planning permission.
Disclaimer: This content is not a replacement for the full codes and standards which are available in full at the following links: https://www.water.ie/connections/Wastewater-Code-of-Practice.pdf and https://www.water.ie/connections/Wastewater-Standard-Details.pdf