WESTERN BAY OF PLENTY GEOLOGY
The Western Bay of Plenty area has a unique soil and geological structure. Much of the land has been made of volcanic material deposited as a result of huge volcanic eruptions.
The volcanic material varies throughout the District in its structural qualities and depth of layers. Some layers are very weak and when wet have virtually no strength.
The relatively steep terrain of the District coupled with high rainfall makes the land subject to instability in many locations.
Known areas of instability include high cliffs around the edge of the harbour, ocean fronting cliffs, and all non-coastal land that is not level. The Minden Rural-Residential Zone in particular is an area of known instability.
Council’s District Plan
contains maps highlighting some known areas of instability. It is important to note that these maps contain limited information and only cover areas where there is a relatively large population.
DEVELOPMENT ON UNSTABLE LAND
Council may agree to a subdivision or accept a building consent application on sites that are unstable, subject to the applicant providing information to Council to show that the site is safe or can be made safe for proposed building work.
Applications for subdivision or building consents on potentially unstable ground will require investigation and reporting by a qualified and experienced soils engineer**. The level of the site investigation and reporting is at the discretion of the soils engineer (except in the Minden Rural-Residential Zone when the level of investigation and reporting is set out in Council’s District Plan).
In conjunction with Tauranga City Council, Council has developed an approved list of soils engineers. We recommend that applicants for subdivision or building consents who require the services of a soils engineer use one featured in the list below. Engineers not on Council's list can be used - However, in most cases their work will be peer reviewed at the applicant’s cost.
Council may require a peer review of a soils engineer’s report. In the majority of cases, the review is an independent and objective quality check on the nature and scope of the investigation to ensure it is in line with Council standards. Council’s policy on peer reviews is as follows:
|Land Type||Soil Engineers Approved by Council (Listed)||Soils Engineers (Unlisted)|
|Minden Rural - Residential Zone||All applications peer reviewed at Councils discretion and at applicants cost||All applications peer reviewed at applicants cost|
|Areas of land instability identified in the District Plan or otherwise known through the Councils records||All applications peer reviewed at Councils discretion and at applicants cost||All applications peer reviewed at applicants cost|
|Other areas||Applications peer reviewed at Council's discretion and cost||All applications peer reviewed at Councils discretion and at applicants cost|
Council and the applicant will agree to the chosen peer reviewer (from the approved list), a quotation will be sought and the cost advised to the applicant.
BUILDING ACT 2004
SOILs ENGINEERS CURRENTLY APPROVED BY COUNCIL
**Note that the term “Soils Engineer” also refers to a “Chartered Professional Engineer” (experienced in soils investigation and reporting), a “Geotechnical Engineer” or an “Engineering Geologist”.
For further information regarding land stability and soil engineers, please contact us on 0800 926 732.