Drainage Works

Drainage Investigation

Substruck Ltd. completes drainage investigation works in response to drainage or subsidence problems or as part of pre-purchase surveys right across Ireland.

Our phase 1 reports document a non-destructive investigation of the drainage system using one or a combination of direct observation, hydrostatic testing, CCTV surveying / inspection and drain tracing techniques.

Direct Observation

Upon arrival at any site, direct observation will tell you a lot about the current condition of the drains before any testing is carried out. We examine the system to determine compliance in relation to construction and siting of access points, ventilation, trip hazards, traps, etc.

Hydrostatic Drain Test

A hydrostatic drain test will verify effective performance of the drainage system to meets its service requirements with regards to water tightness. All drains should be subjected to such a test prior to and during backfilling of drains, to ensure compliance with building regulations.

During the test, pipelines will be filled with water under an approved test pressure for an approved conditioning period, before recording for an approved time interval. The loss will be recorded and compared with the maximum permissible levels or acceptable rates as per WRc plc The Drain Repair Book – Best Practice Manual for the Inspection and Repair of Domestic and Light Industrial Drains (2011), Technical Guidance Document H of the Building Regulations (2016) [post June 1 1992] or I.S. EN 1610: 1998 Construction and Testing of Drains and Sewers, whichever is more applicable. The result will be used to reflect the performance of the pipelines against water leakage, cross connections, depth of cover.

CCTV Drain Survey and Inspection

A CCTV inspection / survey will identify the following:

  • Structural defects (i.e. the physical condition such as broken or collapsed drains, holes, cracks, deformations, etc.),
  • Service defects (i.e. defects that determine the capability of the drain to meet its service requirements and indicate loss of capacity, potential for blockages and water-tightness such as attached deposits, obstructions, roots, exfiltration, etc.),
  • Construction features (features relating to the construction of the drain/sewer such as location and condition of junctions and connections, defective seals, etc.),

· Miscellaneous features such as evidence of vermin, hazardous atmospheres, loss of vision, material, pipe length, size changes, etc.

The CCTV survey report is derived from: CEN EN 135082:2003 Condition of Drain and Sewers Outside Buildings: Part 2 Visual Coding Inspection and WRc plc (2013) Manual of Sewer Classification 5th ed. For a CCTV survey and report, each defect will be assigned a sewer condition grade as per the Sewer Risk Management (SRM5). For a hydrostatic drain test and CCTV inspection, the grade of a length of drain will be based on the worst defect as per WRc (2011).

CCTV inspection/surveying overcomes the limitations of hydrostatic testing, particularly during the identification and location of structural, service, construction and miscellaneous features and defects.

Therefore, Substruck Ltd. advise that a hydrostatic test should not be completed without the aid of a CCTV inspection at the very least. However, as water can travel to areas where a camera unit cannot, we also advise that hydrostatic drain testing can overcome the limitations of CCTV surveying/inspection. Both techniques complement each other to give a more accurate representation of the drainage system.

Drain Cleaning

Drains inevitably get blocked from time to time. Therefore, access points are provided in the drainage system to allow safe and easy access for inspection or cleaning purposes.

Build up of scale, grease, silt and the introduction of foreign objects such as small shampoo bottles and drain rods can eventually reduce the hydraulic capacity of the drain and result in blockages.

Drains can usually be cleared with drain rods but sometimes a more stringent effort is required by use of high-pressure water jetting. Substruck offers a cleaning service for all domestic blockages

Drain Replacement

Drain Repairs

Substruck Ltd. replaces all drainage as part of our subsidence contracts. All drainage is installed to current standards and is subjected to a hydrostatic drain test prior to backfilling and again upon completion of re-instatement.