Hancox, G.T. 1980 Engineering geological investigations for proposed new Mangatewai-iti bridge and approaches. SH2, southern Hawkes Bay. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 346 18 p.
Abstract: Within the next five years the Ministry of Works and Development plan to build a new bridge on SH2 to cross the Mangatewai-iti Stream, about 12 km north of Dannevirke. Sited some 20 m downstream from the existing bridge, the scheme also calls for the realignment of SH2, with the construction of new approaches requiring fills and cut batters of up to 30 metres. The alignment chosen for the approaches was based on a computer study of topographic contours and was primarily aimed at achieving optimum cut and fill balance. However, in view of the weak nature of the materials present at the bridge site, and air photo evidence of mass movement debris under part of the main southern approach fill, doubts were raised as to the suitability of the chosen alignment. Because of these uncertainties the Ministry of Works and Development Napier asked the NZGS Engineering Geology Section (Ref CV2/20) to evaluate and report on the local geology, and provide advice on the batter slopes required for the proposed approach works. A limited geological appraisal of the area was carried out during 1979, in conjunction with MWD investigations which included a laboratory testing programme and restricted subsurface sampling by means of one cored drill hole and one test pit. The results of these investigations are presented and discussed in this report.