From: David Jenliffe
Sent: 07 November 2008 02:22 PM
To: Ian Isaacs
Subject: RE: [SK-Newsletter] re water situation
Hi Ian,
The water supply to the suburb Simonskloof in Simonstown is currently sourced from the Admiral Bierman reservoir (TWL 137m) situated on the southern end of Runciman Drive above Dorian Rd.
The reason for this is that these are gravity fed mains and Admiral Bierman reservoir is situated at a level capable of supplying water to the high lying properties such as Simonskloof , the top of Dorries Drive , Murdock Valley etc. Queen Victoria (TWL 70M) reservoir is the dedicated supply to the Navy and is situated at such a level that it cannot supply the high lying properties above it.
There is a number of reasons that the suburb Simonskloof and the other high lying properties in this vicinity are likely to be the most affected and vulnerable to supply problems.
The main reasons are
· The ageing infrastructure is generally situated below them. This means that every time that a burst main occurs in the vicinity the high lying properties are the first to be affected (gravity).
· The reticulation network in this vicinity is complex. There are several incoming and outgoing supplies and our pump station and reservoir teams are constantly busy managing supply and demand requirements between the various reservoirs, pipelines and the Navy.
· We have reached the final stages of the mains upgrade in Runciman Drive and have completed most of the links into the various streets in this vicinity. Any shutdown required on this main will also affect the high lying properties in Simonskloof.
· The Navy is our biggest Customer in the area and their demands sometimes make it difficult to manipulate the system and maintain supply.
The above are the main reasons for the recent supply problems to Simonskloof and the bullet points below will offer some explanation.
· On the 21st of October a major burst main occurred in Runciman Drive on the existing infrastructure at one of the most complex points linking various supplies in the network. Once the supply was eventually shutdown we discovered that the one 100mm main (concrete encased ? and damaged in 3 places) had subsided and damaged the 375mm main supply to the Navy at the same time. Our teams worked throughout the night (36hr) to restore the supply firstly to the residents and completed the repair on the Navy supply during the day. In the interim we supplied the Navy via a source out of Bierman reservoir.
· During the week of the 27th to the 31st of October we had to manipulate the supply out of Bierman at various stages in preparation for our planned shutdown and connection to the new 200mm main in Runciman Drive. We had one incident during in the week where a leading was damaged during excavation at the proposed connection point and as an emergency we had to shut the supply out of Bierman. This occurred at approximately 14h30 on the 29th. The supply was restored at about 17h00
· On Wednesday the 29th of October we met with the Navy regarding Da Gama Park and their main supply out of Victoria where their minimum night flow is 15l/s. This is affecting our ability to manage the supply to the area. We have given them deadlines to resolve this problem. Daily reports from our flow loggers/recorders suggest that they have a significant internal underground leak. (and also by their own admission) The naval authorities have been instructed to immediately undertake an investigation to determine the integrity of their infrastructure, failing which, their water supply will be restricted.
· During the afternoon on the 30th our reservoir and pump station team had to increase the supply into Queen Victoria reservoir (Navy supply). By opening this supply it reduced the supply to Bierman reservoir resulting in low pressures to the highlying areas during peak draws. This remained the situation overnight. We received an influx of calls early on Friday (initially thought there was a burst) and eventually resolved the problem by shutting the supply into Victoria and diverting supplies. Rodney phoned various Customers to ensure that the supply had normalized. At the time he would have had difficulty explaining the actual scenario.
· We completed the final connection to the southern side of Runciman Drive overnight on the 4/5th of November. This was advertised in the media and warning slips were dropped at the properties most likely to be affected. The job was completed at 04h00 and the supply restored by the following morning.
We still have to install approximately 100 m of main on the northern side of Runciman Drive (below Queen Victoria) before we can connect into a number of existing supplies at this point. We will warn the public well in advance of completing these connections. Once these connections are completed it will increase our ability to maintain the supply to Simonskloof as the existing old supply will be removed, we will be able to supply water in both directions and have the ability to divert water from other sources.
This will do a lot to improve the supply to the area and reduce the risk of intermittent supply in future.
High lying areas are always at risk regarding continuity of supply and Homeowners especially those running bed and breakfasts should consider installing their own storage capacity. There is still many kilometers of old infrastructure that requires our attention, ongoing maintenance and upgrading in Simonstown.
We have informed our District Roads office and the Fishhoek Depot on several occasions of the urgency regarding both a temporary and the permanent reinstatement to Runciman Drive. The ball is in their court.
The Simonskloof community (and other affected areas) must be thanked for their extreme patience (and cooperation) thus far, we therefore apologise for the inconvenience caused to date. (Whilst the ongoing upgrade of the infrastructure continues)
Thanks Dave.
