Chapter B4: Earthworks and Sediment Erosion Control

1 - Introduction

1.1 Scope of this Chapter

This chapter applies to all development involving earthworks in the Kempsey Shire local government area.

1.2 Relationship to Other Chapters of this DCP

The provisions contained in Chapters included in Parts C, D, E and F of this DCP override the provisions of this Chapter to the extent of any inconsistency.

2 - Chapter Objectives

The objectives of this Chapter are:

1. To identify the standards and development requirements for earthworks and sediment erosion control.
2. To ensure that building and construction activities do not have a negative impact on waterways.
3. To ensure that sediment and waste materials derived from construction sites do not cause blocked stormwater pipes, silted streams, poor water quality, or degraded aquatic communities.

3 - Relationship to Council Policies and Other Documents

This chapter may reference relevant Australian Standards and adopt their requirements.

There are no Council Policies specifically focussing on earthworks or sediment erosion controls.

The requirements of the following components of Council’s Engineering Guidelines for Subdivision and Development will apply to earthworks and sediment erosion control:

• D6 - Site Regrading
• D7 - Erosion Control and Stormwater Management
• C211 - Control of Erosion and Sedimentation
• C213 - Earthworks

4 - Development Requirements

4.1 Geotechnical Investigations

Desired Outcomes

DO1 - Geotechnical matters are appropriately investigated and documented prior to lodgement of a development application.

DO2 - Measures to avoid the risk to life and property posed by slope instability are identified and undertaken.

Development Requirements

1. Development applications for site disturbance, excavation or filling (other than for minor building modifications or flood mounds for holding stock during flood events) including, demolition, excavation, trenching and building are to include details of geotechnical conditions at the site and any proposed measures to ensure the site is suitable for the development proposed.
2. Development applications involving a site with potential slope instability issues must include a slope stability geotechnical assessment, prepared by a suitably qualified person, to confirm the site is suitable for the development proposed.
3. Prior to the commencement of construction, detailed drawings shall be prepared and certified by a qualified structural engineer to demonstrate that any improvements, services and/or civil works will be safe, serviceable and repairable, taking into account the geotechnical conditions at the site.

4.2 Earthworks

Desired Outcomes

DO1 - Site regrading and earthworks are undertaken in a manner that:

• Does not detrimentally effect the environmental character of the site;
• Maintains the natural features of the site;
• Provides safe conditions for construction; and
• Minimises the impacts on adjoining properties and developments.

DO2 - Importation of fill material is minimised.

DO3 - Earthworks are undertaken in a manner that prevents damage to stormwater devices installed prior to site works, including swales, infiltration devices, filtration and bio-retention devices.

DO4 - Earthworks comply with the requirements of clause 7.2 of KLEP2013 and AS3798 - 2007: Guidelines on Earthworks for Residential and Commercial Developments.

Development Requirements

1. Site regrading and earthworks are undertaken in accordance with the relevant requirements of Development Design Specification D6 - Site Regrading of Council’s Engineering Guidelines for Subdivision and Development.
2. Earthworks are undertaken in accordance with the relevant requirements of Development Construction Specification C213 - Earthworks of Council’s Engineering Guidelines for Subdivision and Development.
3. Earthworks are carried out in accordance with the approved Specification submitted by the applicant’s Geotechnical Engineer, where relevant.

4.3 Sediment and Erosion Control

Desired Outcomes

DO1 - Erosion and sediment loss before, during and after construction is managed in accordance with either:

• the approved Erosion and Sediment Control Plan; and/or
• the approved Soil and Water Management Plan.

DO2 - Surface and ground water pollution due to erosion, siltation and sedimentation is managed in accordance with either:

• the approved Erosion and Sediment Control Plan; and/or
• the approved Soil and Water Management Plan.

DO3 - Air pollution due to soil loss is managed in accordance with either:

• the approved Erosion and Sediment Control Plan; and/or
• the approved Soil and Water Management Plan.

DO4 - Development on land identified on the acid sulphate soils map complies with the development requirements of clause 7.1 of the KLEP2013.

Development Requirements

1. An erosion and sediment control plan is to be submitted and approved with a development application for development involving site disturbance generally less than 2000m² in accordance with:
   1. Council’s Engineering Guidelines for Subdivision and Development; and
   2. Managing Urban Water Soils and Construction NSW (ie the “blue” book).
2. Where developments involve large areas of site disturbance, a Soil and Water Management Plan demonstrating compliance with the relevant requirements of the following is to be submitted and approved by the consent authority:
   1. Development Design Specification D7 - Erosion Control and Stormwater Management of Council’s Engineering Guidelines for Subdivision and Development; and
   2. Managing Urban Water Soils and Construction NSW (ie the “blue” book).
3. Saving and re-using top soil and the incorporation of additives to improve existing soils is preferred to the importation of soils for landscaping.
4. Sediment and erosion controls measures complying with the relevant requirements of the following are to be undertaken during construction works:
   1. Construction Specification C211 - Control of Erosion and Sedimentation of Council’s Engineering Guidelines for Subdivision and Development; and
   2. The approved Erosion and Sediment Control Plan, where relevant; and
   3. The approved Soil and Water Management Plan, where relevant.
5. The site must be fully stabilised before erosion and sediment controls are removed.