Much has been achieved in a little less than 2 weeks of on site works at the Wetlands. Work was carried out...
Much has been achieved in a little less than 2 weeks of on site works at the Wetlands. Work was carried out on the 9th to the 13th of February, and again on the 2nd to the 4th of March. Several pipes have been installed and armoured at their inlets and outlets, where necessary. This will allow for better flows through the Wetlands, with less erosive force. It also helps with the riparian plantings that have commenced, ensuring the plants don't spend too long inundated under water, in times of heavy sustained rain periods.
Council was guided in these works by Larry Bebbington, author of the "5 Year Remedial Works Program". Larry oversaw the works, and his experience was most appreciated.
The gathering of suitable 450 - 600 mm rock was a real challenge. There is no graded rock of this size in Whyalla, which meant that Council staff and its contractors had to do it. This held us up substantially, and limited the amount of work we could get done. A special thanks to Brent Richards and Micheal Drechsler for their efforts in this part of the job.
The excavation of Kikuyu grass from the in-let drain leading into Pond 1, from Keith Street was one of the first jobs. See Fig. 1. This drain was silting up fast, due to the high sediment loads in the water that flows into the system, coupled with the growth habit of the Kikuyu.
A storm ceptor will hopefully be installed at the head of this drain to one day remove all the sediments and oils from the water, before it continues on into the Wetlands. This will be an expensive exercise, but hopefully one day, will be achieved.
Excavated geotextiled and rip rapped corner of Pond 4 near the SES Compound where water drains into Pond 4 with erosive force. The footpath adjacent was excavated lower and then sealed by the Paveliner to allow for continued foot traffic, and make it resistant to any future erosion. Notice we saved the young tree.
Installed 600 mm drain between Ponds 1 and 4 including cleaning the drain to Pond 4, Geotextile and rip rap were also installed. The inlet to Pond 4 was Pavelined to prevent erosion, and allow for foot traffic. See Fig. 6. Notice we saved a tree in Fig.4.
Cleaned 450mm drain between Pond 1 and Pond 2. It's now ready for geotextile and rock. This is a back up pipe if the new 600mm pipe leading to Pond 4, can't cope.
Installed 2 x 600 mm drains between Pond 3 and Pond 4, to establish a high tide mark in Pond 3 that we have planted into.
We installed a second 1200 mm concrete drain at the Pond 4 outlet. This is to help drain Pond 4 at peak times, and allows us to plant the riparian zone.
Installed two new 600 mm drains leading into Pond 4 from the swale drains from Playford Avenue. The existing drains were installed too low, and one of them completely disintegrated as we tried to raise it. The old concrete pipe in Fig 11 has been blocked up with rock and concrete, to take it out of service.
The drains leading from the inlet pipes to Ponds 3 and 4 were excavated. These dirt and rock drains were severely eroded, and undercut under the concrete spillways and headwalls. Geotextile and rip rap was installed to halt the erosion.
It would be nice to install a Storm Ceptor at the Pond 3 inlet, to capture all the oils and sediments from the Playford avenue drainage system.
The following two photo's are a 'before and after' of the Playford Avenue inlet drain. Note how undercut the concrete spillway is in Fig. 13.
Installed new rock swale drain from Billing Street into Pond 3, where water form the Billing Street area has previously flowed over the gutter, and cut its way down to Pond 3. The drain was lined with geotextile, while the footpath has been Pavelined to prevent erosion.
Excavated geotextiled and rocked the drain leading from billing Street, into Pond 2, that was badly eroded.
We also planted 700 Juncus kraussii (Sea Rush) and Melaleuca halmaturorum (Salt Water Paper Bark) in the intertidal areas of Pond 3 and Pond 4.
The attached Tables are from "L Bebbington (2008) 5 Year Remedial Works Program.
Yellow is completed; light blue is next round of works to budget for. 2008, 2009, 2010, 2011, 2012 - Map of work sites
