Advanced Condition Assessment and Pipe Failure Prediction Project

Activity 3, 4b

October 2014

1. Soil and pipe sampling at pipe failure sites.

1.1 Pipe retrieval

Permanently mark the pipe to identify:

(i)Pipe name/location

(ii)Top of pipe

1.2 Pipe external blasting and scanning

  1. Clean adhered soil from external surface of the pipe, taking care not to remove/damage the external graphitised layer.
  2. Scan the accessible external surface of the pipe with the laser scanner
  3. Remove graphitised-zone layer with external blasting. Leave a strip 20 cm wide around the pipe circumference at one of the pipe ends un-blasted. This is to provide a reference surface for lining up scans. This surface needs to be included in the following scan.
  4. Scan new external surface (exposed cast iron) plus the reference surface.

1.3 Soil sample location

Each main break site will be assessed on a case by case basis in consultation with researchers at the University of Newcastle to determine the best soil sampling location. The method of sampling (either trench excavation or auger extraction) will also be determined on a case by case basis.

1.4 Soil sampling

Soil samples are needed for chemical/LPR analysis and also for bulk density determination.

a. Soil samples for chemical analysis

Figure 1.Soil sample location adjacent to pipe where possible (yellow points – plan view).

  • Collect soil:
  • as soon as possible after the trench has been excavated.
  • from excavated face and in close contact with pipe
  • If trench excavated sample soil at the mid-height of the pipe and (if possible) at bottom and top of pipe (see yellow dots on Figure 1)
  • If soil augered collect a single soil sample at mid height of pipe
  • do not mix samples and note for each sample the position it was retrieved from
  • Each sample should have at least 7.5kg of soil
  • Separate each sample into two sub-samples:
  • (1) 5 kg for soil physical and chemical analyses (see table and details below)
  • (2) >2.5kg sample to be sent to Tony Wells at the University of Newcastle (see details below)
  • Preserve the soil samples in a sealed plastic bags and place in a chilled esky
  • Tag each sample with an ID number, date/time of sampling and location from which soil sampled (GPS coordinates preferred or street location + position around pipe)
  • Express post chilled esky with soil samples to respective laboratories/university (see details below):

(1) 5kg sample for chemical analysis

.

  • List of soil properties and test methods:

Table 1. Soil tests to be conducted.

Soil property / Test method reference(s)
Texture class / AS4419-2003
Moisture content / AS4454-2012 or AS1289.2.1.4-2005
pH / Rayment and Lyons (2011) 4A1 and 4B1 & B2
Resistivity / AS1289.4.4.1-1997
Chloride / Rayment and Lyons (2011) 5A1; APHA Cl B
Sulphate / Bradley et al (1993)
Nitrate / APHA NO3 E
Phosphate / Rayment and Lyons (2011) 9C1
Total organic carbon / Rayment and Lyons (2011) 6B3
Conductivity / Rayment and Lyons (2011) 3A1
Alkalinity (carbonates) / Rayment and Lyons (2011) 19A1
Field capacity / Abbot TS (Ed) (1987) Soil testing service – Methods and Interpretation, Dept of Agriculture NSW (Publisher)
McIntyre, D.S. (1974). In methods of Analysis for Irrigated Soils. (Ed. J. Loveday) Tech. Comm. No. 54. Common Agric. Bur. (Publisher) England
Permanent wilt point
  • Suggested laboratory: For the Hunter Water Condition Assessments we used SESL Sydney. Our contact was Ryan Jacka.
  • If the soil samples cannot be posted the day of sampling, then store the bagged samples in a fridge until they can be sent. Soil samples have a holding time of 7 days.

(2) >2.5kg sample to be sent to University of Newcastle.

  • Please send the remaining bagged soil samples to the following address:

Dr Tony Wells

Civil Engineering Laboratory

Building ED

University of Newcastle

University Drive,

Callaghan, NSW, 2308

  • If the soil samples cannot be posted the day of sampling, then store the bagged samples in a fridge until they can be sent. Soil samples have a holding time of 7 days.

b. Collect undisturbed soil sample for bulk density calculation

Take a soil core with a volumetric sampler at the same locations as specified above for the disturbed soil samples. That is pipe mid-height, and if possible, top and bottom of pipe. Wrap sampler (including soil) in plastic and weigh as soon as possible. The bulk density is determined as the soil mass divided by the soil volume.

1.5Observations and reporting

The following observations will be greatly appreciated:

  • Comment on ground cover (pipe underlying grass, road etc)
  • Comment on the type of backfill surrounding the pipe (native or imported sand surround)
  • Note the presence of rocks, bricks, etc. in the fill
  • Note the presence and depth of the ground water level
  • Take photos showing the environment. Take photos showing pipe in excavated trench.
  • Take photos showing end of pipe and backfill materials
  • Measure and record the depth to the top of the pipe
  • Measure and record the pipe section length (joint-to-joint)
  • Record pipe joint type (take photos)
  • Comment on type of external coating and its condition if any (take photos)

Again please make sure that the sample location for all of the above observations is recorded.

1.6 Site form

A site form is included for reporting if required (see at end).

Site
Site Location
(GPS coordinates or street location)
Date inspected
1. Pipe details
Material
Manufacture date
Manufacture type
Nominal diameter
Average thickness
2. Exposure period
Installation year
Failure/inspection date
3. Corrosion measurements
Measuring device
Maximum pit depth
Location of deepest pit
Depth of general loss
4. Details on external soil environment
Ground cover
Bedding material
Backfill material
Depth to top of pipe
Presence of groundwater
5. Soil properties
Soil sample test results
Date/time sampled
Date/time analysed
Moisture content
pH
Chloride
Sulphate
Resistivity
Conductivity
Nitrate
Phosphate
Texture
Total organic carbon
Bulk density
Moisture content at field capacity
Moisture content at wilt point
Alkalinity (carbonates)
6. Additional information
Section length
Section length inspected
Joint type
Coating type (if any) and condition
Internal lining information