Mansergh, G.D. 1980 Geological report on the Glenbrook lateral, Maui pipeline R12 (N47). Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 345 24 p.
Abstract: A request was received in February from the Maui Pipeline Office, MWD for a report on the engineering geological problems associated with the Glenbrook lateral pipeline rout, the report to follow that being prepared for Huntly to Westfield line. A rapid reconnaissance was made in April and a verbal report was given through Engineering Geology section, NZGS, Lower Hutt which pointed out that the chosen route crossed areas showing evidence of large scale low angle slope failures, these areas usually being associated with the Te Hihi soils as mapped by Orbell (1977). A brief report (included here as Appendix 3) was written summarising observations made on that reconnaissance. The pipeline was then relocated both to bring it closer to Pukekohe, and to avoid the areas of instability. In mapping for the new route a number of sink holes were also located which indicate ground surface collapse. A sink hole was excavated and an immediate report on that feature was written and forwarded to MWD (included here as Appendix 4).