During the sales process, we have advised purchasers that they should expect sites that can be Classified as “S” (for building foundation design). This advice is based on two reports:
- Geotechnical Study of Entire Ecovillage Site, Galt Geotechnics, Dec. 2015
- 46 Test pits across the property
- Preliminary classification of “S” over most of the site, and “A” over sections near the highway
- The report outlines a specific site preparation methodology to be followed to allow the sites to be classified as described, which includes removal of vegetation, stockpiling of topsoil, and then compaction to 0.9m depth (Section 7.3). With additional sand fill, sites can even be brought to class “A” (Section 7.1).
- Technical Memo Site Inspection, Galt Geotechnics, Dec. 2020
- 6 Test pits on specific Stage 1 and 2 lots
- Geotech consultant examined and logged exposed soils within each test pit, and performed dynamic cone penetrometer test adjacent to each pit
- The memo confirms the earlier classification of “S” soils
This report has been accepted by multiple structural engineers as a basis for their design work without additional site testing required. However, some structural engineers undertake their own testing and may come up with a different site classification and design the building footings accordingly. We are aware of one engineer who has been classifying sites as “M.” As the legal liability for the structural integrity of the building lies with the structural engineer, some take a more conservative view and allow for a larger factor of safety.
While most lots have been left at their ‘natural’ levels, there are a handful of private lots where Wormall, our civil contractor, has undertaken earthworks. These are hatched on the civil engineering drawing set. Wormall will be following the prescribed Site Preparation outlined in the Galt report, so we expect the site classification that they achieve to be Class “S.”
Civil Engineering drawings and the Geotech Reports can both be access via our website on the dropbox link: https://www.ecovillage.net.au/library/document-library/
Site Levels, Survey and Drainage
As the site is still under construction it is not possible to get out there to do a site feature survey to confirm final levels. Most sites are quite flat, so this may not be required for design. We did procure a site feature survey over the entire site prior to construction starting, and Peritas has recently provided us with a drawing set for site surface drainage that includes 0.1m interpolated contours (pdfs). This is generally accurate at a whole of site level, but less so at an individual lot level. However, it is the best info we have at this stage. These drawings can be found under the Document Library under Site Levels and Surface Drainage.
These drawings also show nominated shallow swales between every two lots to facilitate surface water runoff and overflow from rainwater tanks. These swales are not constructed but should be considered by lot owners as they are developing their site plans, as they connect in with small swales and culverts in the Community Garden that then connect with the larger drainage swales.
In order to protect against large flood events, we have set minimum finished floor levels for some lots in the Local Development Plans. If you are on one of these blocks, please ensure that you are meeting this requirement. Otherwise, our general recommendation is to ensure that your finished floor level is 300mm or more above the adjacent street pavement (low edge). This approach is appropriate in most cases except for a few lots on the eastern edge of Cluster 1B where the street is higher than the blocks, in which case allowance should be made for any surface water to drain around the house toward the Community Garden.
Sand pads for all of the Groupies lots will be constructed as part of site works by the Developer, which will make construction of those sites by separate builders easier and ensure appropriate interfaces / level changes between lots.
We’ve informed our registered builders of the site level recommendations, but we recommend you discuss this with your builder to ensure the minimum recommended pad levels are followed.
Now that the civil construction for Stages 1 and 2 is nearly complete, we have good as-constructed information on most of the utilities including power (microgrid), NBN, sewer, and irrigation. These drawings can be found on the WEV website under Document Library.
The microgrids include a Site Main Switchboard (SMSB) beside the Western Power connected green dome for each cluster. From the SMSB, power is then distributed through the Community Garden to typically 3 Distribution Boards (DB) around the Cluster. Your lot will have a conduit from the nearest DB to your lot boundary. As part of your build, your builder will need to allow for cabling from the DB (pulled through the conduit) to your house switch board. This avoids having a join at your lot boundary that can degrade and cause problems over time.
We have decided to require all houses to design for 3 phase power (including Groupies). This is beneficial for the microgrid in balancing the power distribution, but also useful for lot owners in future proofing for 3 phase electric vehicle charging. The additional cost in cabling and slightly different inverter is minor, please see latest pricing for 3 phase inverter and solar systems on your Preferred Supply Page.
NBN pits are typically in the street verge and shared by two or more lots. The pits are typically set 900mm off the lot boundary and most are Type 2 pits which are 280x650mm. NBN pits are non-traffficable so if you are planning a crossover or carport nearby, you need to account for avoiding the NBN pit in your driveway design.
The sewer pipework is installed in each cluster and connects to the inside boundary of each lot. The house sewer and greywater system should be designed to connect with this location. The wastewater plant is currently under construction and is estimated to be operational by mid-2021.
The irrigation pipework is also installed in each cluster, and can be accessed from a tap in the border between every two Exclusive Use Areas. The holding tanks for irrigation water have now been installed in each cluster, so the system should be operational as soon as the main pumps are constructed at the dams in late January, 2021. This water is non-potable.