Excavation in Umina Beach
In Umina Beach, check your lot on Council's acid sulfate soils map before settling how deep to dig. Most of the suburb's residential land is Class 4, where works more than 2 metres below the natural ground surface, or pumping that lowers the watertable more than 2 metres, need development consent unless a preliminary assessment confirmed by Council shows no management plan is needed.
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Excavation around Umina Beach
The ground explains why the map matters. The state soil survey maps most of Umina's flat land as the Woy Woy soil landscape, where beach ridges were levelled and swampy swales filled for housing, and says the watertable generally sits within 2 metres of the surface, usually 50 to 150 centimetres down in the swales. It lists non-cohesive soil and permanently high watertables among the landscape's limitations. A hole in sand like that may need its sides supported and its water pumped out, and pumping is itself one of the works the acid sulfate rule counts.
The escarpment on the western side is different ground. The same survey places the Watagan soil landscape along the escarpment west of Umina and lists a mass movement hazard, steep slopes and occasional rock outcrop among its limitations. Council's geotechnical chapter asks for a geotechnical report where slope and geology put a lot in its higher hazard categories, so on that side a cut into the hill is an engineering question before it is a machine one.
Permits and Central Coast Council rules
A pool or an extension here can still go through a complying development certificate, but on Class 3 or 4 acid sulfate land the Housing Code caps the excavation at 1 metre deep, wherever it sits on the block, so a deeper dig goes through a development application. Much of Umina's housing is also inside Council's flood planning area for Woy Woy and Kahibah Creek, where cut and fill needs Council's approval.
Source: Central Coast LEP 2022 cl 7.1 and Acid Sulfate Soils Map; Exempt and Complying Development Codes SEPP 2008 cl 3.30(2); Central Coast DCP 2022 Chapters 3.1 and 3.7 — confirm current requirements with Central Coast Council.
Our Umina Beach service area
An enquiry from Umina Beach is referred on to an independent local provider, who contacts you to look at the block.
See all Excavation on the Central Coast. We also work in Woy Woy next door, where the acid sulfate class is different.
Call (02) 4326 8289Last reviewed · Updated · First published