4.20  Water and Drainage Systems

The Contractor shall provide separate foul and surface water drainage systems. The drainage systems shall provide safe effective removal of wastewater and surface water from the Facility and be compliant with all relevant environmental and health and safety Legislation.

Car park drainage to be fully compliant with Environment Agency requirements for interception.

The Contractor shall ensure that fatty wastes are properly intercepted and appropriate arrangements made for disposal.

(a)  Above ground (building) drainage systems

The requirements for drainage systems internal to buildings are contained in paragraphs 3 (Architectural Requirements).  

(b)  Below ground foul drainage system

All installations shall conform to the requirements of "Sewers for Adoption and the Building Regulations".

(c)  Surface Water Management

The Contractor shall design and construct a surface water drainage system to serve the Facility, incorporating as necessary, balancing, storage, semi-permeable surfacing for car park areas and other means in order to reduce peak flows and improve the quality of surface water discharge.  

Surface water discharge shall be designed in accordance with the following order of preference / hierarchy:

(i)  a Sustainable Urban Drainage System (SUDS) designed and constructed in accordance with Guidance and in particular the guidance contained in "SUDS: Design Manual for England and Wales";

(ii)  an outfall to a watercourse that complies with any notice and/or consent by the Environmental Agency;

(iii)  a public sewer provided under the "Sewers for Adoption 5th Edition".

(iv)  SUDS features shall be designed as an integral part of the landscaping.

The Contractor shall design the surface water drainage system to avoid the risk of local flooding and flooding of the system into which it discharges.  The design of the system shall ensure that there are no areas of standing water.  The Contractor shall check the design and flooding return periods, design storms and provide the necessary overland flow routes to safely route the surplus surface water runoff away to meet the requirements of the Environmental Agency.

The surface water drainage system shall be designed to require no regular maintenance other than the cleaning of gully traps, petrol interceptors etc, and shall be capable of taking such detritus as may normally arise during the operation of the system.  Access for maintenance shall be provided to all drainage runs.  The design of the system shall be such as to create the minimum disruption in the event of blockages.

(d)  Sewage and Water Sewers

The Contractor shall provide a foul water drainage system which shall provide sufficient capacity to accept peak flows for the Facility. The design of the system shall be such as to create the minimum disruption in the event of blockages.

The Contractor shall provide, where necessary, any isolators, retention traps, interceptor tanks and other such devices necessary to prevent the discharge of any potentially dangerous or otherwise contaminative materials to the public sewers.  The installation and operation of the system shall meet the appropriate requirements of the local Water Authority and the Environment Agency.