Sewerage pond open day
TDC utilities area manager Jeff Cuthbertson (right) explains the Rapid Infiltration Basin trial to Waitapu Rd resident Franca Morani. Photo: Gerard Hindmarsh.
An open day at Takaka’s wastewater treatment plant off Haldane Road last Friday (17 Feb) drew around three dozen visitors, including TDC Mayor Richard Kempthorne, GB Community Board councillors and more than a few neighbours following the smell of a permanent solution to their wafting neighbourhood problem.
Council, Montgomery Watson Harza and Downer staff took the opportunity to explain their $3.4 million planned upgrade for the plant, which has now reached full capacity. Council admitted the plant “has not been able to consistently comply with [its own] existing resource consents”, particularly when it comes to odour.
Jon Krause, MWH’s project manager for the upgrade, said that doing nothing was simply not an option now.
“It’s an aging system which is close to the town. It’s handling growing volumes of wastewater and we have had odour concerns expressed by the public.”
Last upgraded in 1996, Takaka’s wastewater system (which extends from the end of Waitapu Rd through to Tata Beach, back up through Takaka to Park Avenue and over to Dodsons Rd) now services a permanent population of 2500, which doubles over summer. Two 30-hour-a-week sewerage technicians are employed to keep the sludge moving through the 22 pump stations throughout the sewerage collection area. In winter, it can take 10 days to pump sewerage from Pohara to the treatment plant in Haldane Road; this doubles in speed over summer. Waste from pumped septic tanks and waste-holding tanks (called septage) which is collected from within Golden Bay is also discharged into the main 80m x 80m oxidation pond. Currently the treatment plant is made up of two big oxidation ponds, totalling just over one hectare, which dispose into two big, elongated marsh cells with their associated disposal trenches.
A working group (made up of the Mayor, councillors, community board members and local residents) formed in February last year to establish and agree upon an upgrade with council technical staff. New “treatment components” now planned include an automated screening chamber with odour control, new oxidation ponds, a constructed wetland and a dedicated septic receiving facility.
Council staff have already undertaken site investigations and extensive trial work, including the installation of a Rapid Infiltration Basin in an adjoining field. Basically a bunded-up gravel soak pit, it receives the processed wastewater as discharge (which is invariably odourless during this “dosing’ stage), which then quickly soaks back into the gravels. Monitoring of water flows under the gravels in the vicinity has so far shown the discharge, once underground, filters out northwest towards the river, avoiding town and also the Te Kakau Stream.
Feary Crescent resident Giuliana Morani attended the open day (with her sister Franca Morani from Waitapu Rd) and questioned the expense of the high-tech project.
“It shouldn’t be about building something bigger! More effort should go towards encouraging composting systems and educating people about reducing their wastewater output.”
Jon Krause admits that such concepts have gained considerable support. “But in the end there will always be seepage and wastewater to deal with from sinks, bathtubs and washing machines, stormwater too. That all presents a high risk of groundwater contamination if it’s not processed properly.”
The working group will be submitting its final recommendation to TDC’s Engineering Services Committee next month, and work on the upgrade is tentatively scheduled to commence in June 2013, pending a government subsidy for the project.
Gerard Hindmarsh
