St George Showground GAB Bore Construction

⁠⁠⁠Overview

Balonne Shire Council invites tenders from suitably qualified tenderers for the decommissioning of an existing bore (RN397) on Henry St, St George, and the construction of a new bore from the Gubberamunda Sandstone aquifer of the Great Artesian Basin (GAB) at St George Showground.

Scope

The scope includes:

• Decommissioning of the existing bore (RN397) on Henry St, St George
• Drilling, casing, cementing, developing and testing of a new artesian bore from the Gubberamunda Sandstone aquifer of the Great Artesian Basin at St George Showground for the St George water supply
• Supply of a wellhead on completion to control artesian conditions

Bore Design

Based on available data, the bore will be artesian. Balonne Shire Council has nominated a production rate for the bore in the order of 150-200 ML/yr (4.8-6.4 L/s). The bore is to be constructed to take underground water only from the Gubberamunda Sandstone aquifer of the Great Artesian Basin (SARA Condition No.2). Hydrogeological assessment indicates that a suitably constructed bore within the Gubberamunda Sandstone will likely yield, under free-flowing conditions, between 8 L/s (operating) and 23 L/s (maximum). As the bore is likely to be artesian, downhole pumping infrastructure will not be required.

An eight-inch nominal bore has been designed (schematic shown in Appendix B), allowing for the following:

• Mild steel conductor casing of 13 3/8 inch nominal diameter, installed to allow for movement of surficial soils, with depth determined on site by the Class 3 driller based on geology encountered
• Mild steel surface casing of 10 3/4 inch nominal diameter, cemented in place within competent lithology to a depth of 150m
• Mild steel production casing of 8 5/8 inch nominal diameter, installed to a depth of 980m
• V-wire wrapped stainless steel screen of 6 inch nominal diameter, extending 10m inside the production casing (slotted casing may be installed as an alternative to the screen)
• Borehole diameter determined by the Class 3 driller in accordance with the minimum borehole diameter requirements from the "Minimum construction requirements for water bores in Australia – 4th edition"

The drilling and final bore casing shoe and total depths and construction will be guided by the geological conditions encountered and logged by the on-site geologist/hydrogeologist. Decisions on construction depths and critical construction elements will be agreed between the Principal, the lead driller and the geologist/hydrogeologist during the drilling programme, with the final decision on bore construction determined by the lead driller in accordance with their Class 3 Water Bore Licence conditions and responsibilities.

Contractor Requirements

• The drilling contractor must be a Class 3 licensed driller holding a Queensland water bore drillers licence
• Experience in drilling and constructing water bores to similar depths and capacity
• All work performed under the contract must meet the minimum construction requirements for water bores in Australia and any other requirements of the Department of Resources

Instructions to Tenderers

All queries and requests for information must be submitted through the Vendor Panel forum portal, to ensure all tenderers receive the same information at the same time.

Location

• Existing bore decommissioning site: Henry St, St George
• Map: View on Google Maps
• New bore construction site: St George Showground
• Map: View on Google Maps