Riddolls, B.W. 1973 Geological investigations for Porirua sewage tunnel and treatment plant site. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 170 4 p.
Abstract: The Porirua City Corporation intends replacing the existing raw sewage outfall near Titahi Bay. The corporations consulting engineers, Messrs. Truebridge, Callender, beach and Co.,, have recommended that a new outfall and treatment plant be situated at Kaumanga Point. The scheme requires construction of a tunnel approximately 2.5 km (1.5 miles) long from the Porirua Valley to the coast. It has been proposed that the intake portal be situated in the valley of Takapuwahia Stream, to the north of Porirua City ((Fig. 1). The area was visited with Mr D.N. Williams, in August, 1973. (auth)