Environment Canterbury urges buyers to check wastewater systems on rural properties
Buying or building a rural or semi-rural property? Make sure you know where the wastewater goes, says Environment Canterbury.
A reliable liner for containing dairy effluent depends on pond system design, material selection and quality installation, the company says.
Swannanoa, North Canterbury dairy farmer Brian Tinomana commissioned Viking Containment to supply and install the liner for his new dairy effluent pond.
The liner material selected was Agrishield 1.5mm high density polyethylene (HDPE) geomembrane; it is extremely tough, durable and compatible with animal fats. The 1.5mm HDPE liner at 1 x 10-14 also exceeds resource consent permeability requirements of 1 x 10-9 m/s. Thus it prevents effluent leaking and contaminating the environment.
1.5mm HDPE has a long history of proven performance and reliability and is often specified for wastewater applications for council and large civil applications.
Safety also features prominently on Tinomana’s farm. Because the side slope surface of a lined pond is very slippery, especially when wet, Geoladders were installed to allow safe access for emergency evacuation of the pond, and they can be used during maintenance, when servicing pumps or control equipment. The Geoladder has a colour coded depth indicator which relates to the DairyNZ pond calculator volume gauge.
Says Viking, “Before commencing the liner installation it was important that the subgrade surface and compaction met the specification. The pond design and earthworks construction was completed by Worthington Contracting Ltd. A protection geotextile between the liner and the sub-grade was also utilised to cushion the liner.”
For liner installation and testing the same exacting standards required for municipal wastewater treatment ponds also apply to dairy effluent applications. Liner installation undergoes comprehensive quality control and assurance including subgrade acceptance, manufacturer’s material data, panel layout, liner deployment, seaming, testing and warranty information.
To collate and record all the results and data, Viking has gone ‘paperless’ and developed a new electronic quality assurance system for geosynthetic liner installations.
Quality assurance and health and safety data are recorded in real time in the field on a tablet, ensuring accuracy and complete capture of data. The program is structured to cover all steps of the installation with key elements that must be completed before progressing to the next section. This ensures the required data is recorded and that the project meets the specification. And it enabled the company to promptly present the farmer with a complete QA report at the end of the project, which was used for compliance.
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