When Deborah Williams sought resource consent for alterations to her Herne Bay villa she needed to source extra information for Auckland Council.
The council needed reports on:
- overland flow effects and
- increase in site coverage/stormwater run-off
Envivo civil engineers are experts in these areas. Envivo civil engineers were engaged to prepare a site drainage report covering off both issues:
- At the exact spot where additions were proposed council plans showed an overland flow path in the rear of the property. Council data is not always accurate, which means investigation needs to be undertaken and the issue addressed for resource consent. Auckland Council has an Auckland-wide flood modelling map that they use to ascertain flood risks for the region. For the overland flow, Envivo used 3d site data to model the apparent flow path in the rear of the property, demonstrating inaccuracies in Council’s data, and showing that the apparent overland flow path need have no bearing on the proposed development.
- The home’s existing system has stormwater and wastewater in the same pipe. Any increase in the impervious area needs to be controlled so that flows from the site are kept the same as pre-development levels. In order to achieve this Envivo engineers prepared calculations for a stormwater detention tank to detain flows from the roof area and release them slowly into the network at a rate to match the current run-off. Working closely with the architects, Creative Arch, we prepared a specification for a tank that would work beautifully with the proposed development. A ‘slimline’ option was proposed to the owner that installs neatly under the eaves of the dwelling, is environmentally friendly and tucked away – yet easy to access for future maintenance.