4. Survey Type A: Verification

When requesting verification by excavation, the client should include the following text in the specification document:

Undertake a Survey Type A: Verification by Excavation survey, as defined in Section 10 of PAS 128:2022, of the required site area (reference to the search boundary plan to be provided by the client).

The survey shall identify and include:

01. Trial pit/trial hole/slit trench [delete as appropriate] to be excavated to a width of XX metres and depth of XX metres or to a width and depth that is safe and practical to do so.*

02. Information gathered from an exposed utility within an excavation shall as a minimum consist of:

• a) nature of utility (such as pipe, cable or other)
• b) configuration of multiple utility layout
• c) diameter of utility (external diameter only)
• d) material type e) backfill materials used
• f) observation of the condition of utility
• g) prevailing ground conditions
• h) appropriate imagery to be captured of the exposed asset and environment – in line with the requirements of the client.

03. When backfilling a hole or trench any material used shall be compressed and tamped down to avoid subsidence. Any wearing course will be replaced with a like-for-like material, unless otherwise instructed.

04. Fees should be included to cover any excavation permit, safe systems of work and supervisor under the New Roads and Street Works Act 1991 (NRSWA) as appropriate.

Verification Types

Survey Type A: Verification can be by one of two different visual inspections, as defined in Section 10 of PAS 128:2022:
  - Inspection via a manhole chamber, inspection chamber and/or access point; or 
  - Exposing the utility and subsequently measuring and recording its accurate location as well as other relevant attributes through excavation.

Survey Type A by excavation can be the ideal way of confirming the exact position and depth of a utility detected previously via Survey Type B techniques. Strategic positioning of verification trial holes can considerably aid design and build. Verification by excavation can be undertaken by either vacuum or suction excavation or by hand-dug or machine-dug trial pits.

If excavating on the public highway, which includes footpaths, it is mandatory to obtain an excavation permit from the local authority. Many providers of verification by excavation will be able to arrange this. *The surveyor can advise on this if the client is unsure what to specify.