BS EN 13508-1:2012 pdf download – Investigation and assessment of drain and sewer systems outside buildings Part 1 : General Requirements
c) investigation as part of the development of a specification for works to implement all or part of an integrated sewer system management plan;
d) the investigation of a drain or sewer system following an incident in order to determine the maintenance requirements;
e) an investigation of the resilience of a drain or sewer system to various hazards or threats.
5.3 Determine the scope of the investigation
The scope of the investigation should be determined, including:
a) the geographical extent of the investigation;
b) the level of detail at which the system is to be investigated (e.g. at strategic level of whole catchment,more detailed level of sub-catchment or detailed level of components);
c) which components of the system are to be included in the investigation;
d) which aspects of condition or performance are to be investigated for example:
1) protection from flooding (see EN 752:2008, 5.1.2);
2) maintainability (see EN 752:2008, 5.1.3);
3) protection of surface receiving waters (see EN 752:2008, 5.1.4);
4) protection of groundwater (see EN 752:2008, 5.1.5);
5) prevention of odours and toxic, explosive and corrosive gases (see EN 752:2008, 5.1.6);
6) prevention of noise and vibration (see EN 752:2008, 5.1.7);
7) sustainable use of products and materials (see EN 752:2008, 5.1.8);
8) sustainable use of energy (see EN 752:2008, 5.1.9);
9) structural integrity and design life (see EN 752:2008, 5.1.10);
10) maintaining the flow (see EN 752:2008, 5.1.11);
11) watertightness (see EN 752:2008, 5.1.12);
12) not endangering adjacent structures and utility services (see EN 752:2008, 5.1.13);
13) inputs quality (see EN 752:2008, 5.1.14).
e) the extent to which each aspect of condition or performance is investigated;
f) the interactions with other parts of drain and sewer systems;
g) the external influences on the system and its components (e.g. soil conditions, traffic loads);
h) the interactions with other infrastructure (e.g. other utility services, urban environment);
i) the resilience of the system.
The scope should be set to enable the likelihood and consequences of all significant performance deficiencies to be described. Records of past incidents and any other relevant information should be brought together and a detailed review should be carried out to establish the scope of the investigations.
Past performance can be established from existing records, including:
i) records of flooding incidents;
ii) pipe blockage incidents;
iii) sewer collapse incidents;
iv) rising mains failures;
v) disease, injury or fatal incidents to operators;
vi) disease, injury or fatal incidents to members of the public;
vii) sewer damage incidents;
viii) compliance with discharge consents into and out of the system;
ix) closed circuit television (CCTV) survey and visual inspection data;
x) wastewater related odour complaint incidents;
xi) hydraulic performance analysis;
xii) performance of mechanical/electrical equipment;
xiii) results of monitoring, performance and condition of flow control structures;
xiv) sewer surcharge incidents;
xv) groundwater contamination incidents.
Information about possible future changes in the systems should also include:
 new developments;
 other infrastructure works.
The costs and benefits of collecting information and carrying out investigations should be considered, taking into account the known performance problems in the system and any requirements of the relevant authority.
5.4 Review existing information
The collection and review of all available relevant information about the sewer system shall be carried out and is the basis from which all other investigations are subsequently planned. This information should include historical records. In addition to the performance information listed in 5.3, examples are:
a) inventory, including the items listed in 5.5;
b) relevant permits and legal requirements;
c) previous operational, maintenance, structural and safety measures to overcome the problems and associated costs;
d) nature and quantities of trade effluent;
e) previous inspections;
f) previous hydraulic measurements (flow, depth, velocity);
g) results of previous hydraulic calculations or hydraulic models;
h) previous assessments of environmental impact;
i) existing drain and sewer condition data;
j) receiving water quality and use;
k) groundwater levels and velocities;
l) ground type and conditions including infiltration capacity;
m) groundwater protection zones;
n) previous test information;
o) characterisation of wastewater;
p) information on proposed new development or redevelopment within the catchment area;
q) records and forecasts of traffic volumes;
r) results of previous investigations.
Some of this information can be available from as-constructed drawings.