BS EN 13508-1:2012 pdf download

BS EN 13508-1:2012 pdf download.Investigation and assessment of drain and sewer systems outside buildings Part 1: General Requirements.
5.5 Update Inventory as required
The inventory infomiation Is used by all the other investigations. Where the review of existing information (see 5.4) condudes that the inventory is incomplete it shall be updated so that a sufficient record of the drain and sewer system is available to carry out the other investigahons. After review arid updating, the inventory of the system should contain the following information, for example:
a) For eadi dram or sewer system:
1) the type of system (e.g. combined system or separate system);
2) whether the system is a gravity system, a pressure system or a vacuum system,
b) For each drain or sewer pipe:
1) thelocationofthep.pe;
2) the depth of cover and invert levels at the upstream and the downstream ends of the pipe;
3) the shape. size (e.g. diameter) and material.
C) For each manhole or inspection chamber:
1) the cover level and Invert levels;
2) the dimensions and materials;
3) the connecting pipes.
d) For each pumping stabon;
1) the number and the flow and discharge pressure characteristics of the pumps:
2) the dimensions of the wet well.
e) For each other ancillary structure:
1) the dimensions of the structure;
2) the connecting pipes:
3) details of ancillary equipment (e.g. valves, flow controls),
The survey method used should rettect the scale and level of the investigation and can include:
i) physical surveys (e.g. to determine the dimensions of accessible pipes, chambers and other features);
ii) terrestnal survey techniques (e.g. to determine the location and level of the features):
iii) global positioning system (GPS) for the position and level of surface features;
iv) light detection and ranging (Lidar) is a technique for the determination of the surface profile of the ground from aerial surveys.
5.6 HydraulIc Investigation
5.6,1 Introduction
The aim of the hydraulic investigation is to establish the hydraulic characteristics of the flow in the drain and sewer system, the available capacity in the system and the extent of any surcharge and flooding.
The investigation techniques include:
a) flow and water level measurement:
b) rainfall measurement;
c) hydraulic calculations:
d) other techniques.
5.6.2 Flow and water level measurement
Velocity and depth sensors can be used in drains anti sewers to measure me ttows, iong or won term now measurements cen be used to:
a) investigate the hydraulic characteristics of foul wastewater flows;
b) investigate the extent and location of entry infiltration;
c) investigate the extent and location of any other extraneous water e.g. flow through gaps in maririole tops (between the cover and frame) or wrong connections;
d) Wi combination with rainfall measurement (see 5.6.3) to validate hydraulic calculations (see 5.6.4).
The sensors used should be selected so that they are capable of achieving an acceptable accuracy over the full range of flow conditions expected. Measurement sites should be selected so that they avoid excessive turbulence or other factors which could lead to unacceptable measurement errors. Periodic checks should be carried out of the accuracy of the sensors.
5.6.3 Rainfall measurement
Rainfall measurement is commonly used in oon unction with flow measurement (see 5.6.2) to investigate the surface water and other rainfall related flows in the drains and sewers. The rainfall intensity should be measured at time intervals appropriate to the sewer flow simulation model being used
Rainfall intensity across the catchment of a drain and sewer system can be measured using a network of recording raingauges which should be spaced sufficiently closely to measure the spatial variation in the rainfall. Where possible. use should be made of official meteorological recording stations. However, where these do not provide sufficient coverage, additional raingauges should be provided. Raingauges should be selected that are capable of accurately recording the expected rainfall intensities. The raingauge sites should be selected to minimise the effects of any local meteorological effects (e.g. local cross winds) that could adversely affect the accuracy or the measurements.