When a new house is built in an old suburb the drainage aspect of the construction needs to be carefully thought through. This is particularly so if the suburb is in a low lying area that is prone to flooding.
The surrounding old houses well generally always be raised on piles, but it is highly likely that the local council will insist on the land for the new house being raised significantly by adding a lot of fill. This can be an expensive proposition for the homeowner, unless they have good contacts in the earthmoving sector and are skilled at negotiating good deals. For example, if the homeowner can find a landscaping contractor who is wanting to get rid of many truck loads of fill, in the homeowner may be able to save themselves around $15,000 and save the landscaping contractor around $10,000 by simply getting the contractor to dump the fall on their land and to level and compact it.
New houses in old suburbs in almost all concrete flooring, and this means that the drains will exit out from the concrete foundations at a level significantly higher they’re in for the adjacent older houses. This means that the slope of the new drain down to the main sewer pipe will be steeper then for the adjacent houses, and therefore far less likely to block at some stage in the distant future. The adjacent houses will all be using short lengths of earthenware pipes for the sewer, and over the decades this piping is prone to intrusion by tree roots, to sinkage and settlement of the ground around, anti breakage.
Consequently for drainlayers almost all their repair work is too old earthenware piping. Modern sewage piping is made out of long life and very tough PVC, and is installed in long continuous links, and joined with very strong PVC glue, and this piping is virtually impervious to tree roots and damage from settlement etc. This piping is installed on a reasonably deep bed of free draining gravel and the trench is then topped up with more gravel, which makes for a very strong surrounding bed for the piping.
New house construction means that a new sewer line is installed out to the main sewage line in the street or in council reserves. For the drainlayers in North Shore this can present tricky problem but it’s the main sewer line was installed many many decades ago, there’s the sewer could be hard to find and difficult to access because of subsequent building all paving work that may or may not have been approved by council consent.