Results of Soil Testing & Wastewater Management

Sven Nielsen (Geotech Engineer) has provided his Soil Tests and Waste Management Report (the latter a requirement given that we don't have access to town sewerage and therefore need to have an onsite wastewater system.
While we are awaiting the (potential horror of the) preliminary costings for the driveway designs from the Civil Engineers, we thought we would update you with the outcome of the soil testing.
An extract of Sven's report notes that:

The site is underlain by Triassic Sandstone bedrock and is proximal to a contact with Jurassic Dolerite. The clay fraction is likely to show moderate to high ground surface movement and the soil may lose bearing potential when wet. The soil is likely to be variable in depth with colluvial cobbles and boulders to be expected throughout soil profiles over the site.
It is noteworthy that minor gully erosion (indicative of dispersive soils) was observed immediately to the north of the proposed house site. A soil sample from bore 2 was subjected to the Emmerson Test with a Class 4 (non dispersive) result. It is likely that the stratified clays associated with various weathering phases of the sandstone bedrock will show a range of dispersive classes over the proposed development area. This has implications for both recommended founding layers of any footings solution as well as the management of both stormwater and wastewater over the site. The development proposal involves significant site cutting into the underlying sandstone bedrock. The strength and hence excavatabilty of these rocks will vary over the site given their sedimentary nature, and unconfined compressive strengths (UCS) of up to 75 MPa are considered representative of harder rock phases over the site.

It looks like we should hopefully be able to excavate for the building site in its proposed location, with a sublayer of "rippable" sandstone (ie it won't need to be removed by dynamite!) and also have the foundations going directly into the bedrock.
The Soil Test Class was returned as M (standing for "Moderate Movement"), but for the purpose of building, if we are to put the foundations on the bedrock, we would instantly graduate with a Soil Class A.
Turning to the wastewater treatment, after spending a disproportionate length of time looking at composting toilets Viktoria and the Android elected to go with a septic system with raised absorption beds. To incorporate a composting toilet with a chute or external chamber would require significant redesign of the bathroom to accommodate it. And as for the ones with the internal compost chamber... they really are possibly the ugliest creatures ever invented.

Even superimposed on the ocean... they're still hideous

So, given the legal requirement that even rooms that could potentially be used as bedrooms (ie Viktoria and the Android's individual studios) be listed as bedrooms on the Council application, our downsized house is once again a 4 bedroom house and, as per Sven's recommendations:

It is proposed that this dwelling be serviced by a dual-purpose septic tank with effluent dosed into raised absorption beds. The absorption area could be catered for as two 10m x 3.5m raised absorption beds (core bed dimensions) shown on the site plan with adequate room for a 100% reserve if required. Care should be taken to ensure adequate setback distances from boundaries and sensitive down slope environmental receptors where applicable and installation should be compliant with the prescriptions contained within this report. Given the site investigation has been conducted prior to earthworks, further site inspection should occur after site works have been finalised. Bed locations may be relocated at this time. It is recommended that a standard domestic 4000L Dual Purpose Septic Tank and pump well be installed to accept and treat effluent flows.

Neal-the-Architect has intimated at a few design improvements to the house itself which will be on their way, but we don't anticipate receiving any of these until after Neal returns from his family vacation in the next couple of weeks.

Soil testing... a tale of dirt and mountains

Soil tests are a big deal. No, really.
Not only will the results of the soil test impact the driveway design and the foundation design, they will ultimately give us an idea of whether we will be digging through dirt or stone, and thus how much this whole extravaganza will cost. But there is a third thing. Because our land is rural, we don't have any connection to town sewerage. So the type of on-site wastewater treatment system we can are able to install is also dependant on the type of soil.
And that's before the building even gets out of the ground.
We engaged Sven Nielsen from Strata Consulting to perform both the soil testing and the on-site wastewater management plan for us. Following a meeting with Neal-the-Architect, Sven advised that he would...

...propose to drill three bore holes to 2.5 meters in depth (or refusal on rock) across the footprint of the proposed dwelling.  This will give us and understanding about soil depth and composition across the footprint which will help to inform the suitability of the site for cutting as per the current plan.  This will also allow sampling of clays which will be submitted to the laboratory for the Atterberg Limit test which will give us the site classification details.  Given that I cannot get vehicle access to this area to use my vehicle mounted drilling rig I will use a man-portable drilling rig for this. 

The engineers also require soil bearing capacity determinations for the foundations as well as CBR (Californian Bearing Ratio) determinations for the driveway.  I will gather this information using a dynamic cone penetrometer and present this information in my report - we will need to do a test at each borehole as well as at 4 locations along the driveway.

That all sounded very impressive, although it did leave The Android feeling he was slightly incomplete without a dynamic cone penetrometer of his own. 
As we have tried to prepare ourselves for this journey on the basis that there will be monsters hiding around every corner, and what can go wrong probably will, we were not completely surprised when we heard again from Sven shortly after he had conducted the site testing and...

...discovered some tunnel erosion near to your proposed house site.  This is caused by dispersive soils (soil which dissolve in water) and is nothing to be unduly worried about but it does have implications for the management of storm water runoff and wastewater from your house as concentration can lead to further erosion and instability.  

I suggest that we subject a soil sample to a dispersion test, which will quantify how dispersive your soils are. This will help to inform management strategies in terms of your storm and wastewater, including the treatment of disturbed areas.   

Let me know if you want me to commission this test or if you have any questions.

Naturally, we requested that Sven proceed with the additional tests, believing it would be prudent that we get as much information as possible. We don't want to end up with a wastewater system that is inappropriate any more than we want to have the house sliding down the mountain after the first downpour. 
On receipt of Sven's report, the structural engineers will be able to complete their costing estimates for the driveway, we will have an idea of the type and cost of wastewater treatment system we can install, and Neal will be able to determine where on the block we can finally settle the house.

TIP: When it comes to building in remote areas, patience is definitely a virtue.

Driveways.... an engineering extravaganza

My word! Who knew planning a driveway would be so complicated?! A driveway people!
We are currently traversing the strange "Driveway Neverland" inhabited by Civil and Geotechnical Engineers. Although slowly learning to speak their language, we are still largely confined to making hand-gestures to make ourselves understood.
What is all boils down to is us having two driveway options... the first is favoured by those from Clan Engineer, while the second is favoured by Viktoria and the Android and Neal-the-Architect.
Following are the untranslated comments regarding the two options from Gandy & Roberts Consulting Engineers (as an aside, it's worth clicking on their name to visit their website if only to read about their forays into experimental siege engine research...)

I have done a quick design for both options. Design constraints included a maximum grade of 25%. Batters slopes have been done at 1:1.5 - this may be steepened depending on the geological situation.

Road 1 - Is the shorter of the two options (therefore less costs) and cuts across the contours better to achieve a better balance between earthworks required  and maximum grades used.

Road 2 - I have used a batter slope of 1:1 for the first 40m (may need stabilised batters), otherwise we would be cutting into the existing road formation. It is much longer with a more complex geometry. The hard part with this road is the turn at around Ch 60. Trying to achieve grades of not more than 25% when cutting perpendicular to the contours presents much larger earthworks.

Road 1 would be the better option (cost and construction wise) but does not enter from the north as the client wanted.

Following are the two design options, as provided by Gandy & Roberts. Bear in mind there is about 50 metres of land (in a straight line) from the left hand side of the picture to where the house outline begins.



Road 1 leading to (outline of) house



Road 2 leading to (outline of) house

So do we go with practical and less costly, or prettier and a small ransom? We are yet to make a decision as we won't get an idea of costs until some more geotech information has been gathered.
Do you prefer one design over the other?
Let us know what you think.

Follow our Blog!

Viktoria and the Android have made a quantum leap in blog technology, and given you the option to FOLLOW us on our journey (okay, so it's hardly a new discovery...)
To follow our blog, click the "Join this site" button on the right hand column.
After you sign up, you will see a popup window with the options to either follow publicly or privately. If you decide to follow our blog publicly, your profile picture will automatically be displayed on our blog, together with a link to your profile.
There's plenty of room in the Time Machine, so jump on board.

Feedback to the architect - round 2

We have finally managed to get our collective brain organised, and have compiled feedback on the second lot of sketch designs developed by the architect.
Attached below is a copy of the floor plans which we scribbled on, a summarised version of the feedback we provided to Neal-the-architect and some photos of other buildings and interiors which we have taken as inspiration. We had to make the floorplans larger so that they were legible, but unfortunately this means that they look a bit untidy on this page.
We would love to know what you think of the designs - or if you have any suggestions!



Ground Floor Plan with comments from Viktoria and the Android


Living room

• swap the full length sliding door for a window (allow some opening for ventilation)
• the fire place is to be a slow-combustion woodstove with a water boiler (Thermalux and Scandia are the two Australian ones we were considering)
• we liked the idea of the 'sunken living room' option discussed, and this may turn out to be more practical given the slope of the land

Flooring

• in the event that polished concrete is outside our budget, we have found a photo of the type of tiling we both like - large format, in a standard grid pattern, with matching grout (no white!)

Picture of the type of tiling we like

Desk / study

• move the desk from the end of the hall, and spin it 180 degrees so that it is facing the pantry wall
• the media hub / phone etc would therefore be nearer the kitchen area
• include an internal sliding door (emerging from the wall between the entry & pantry maybe?) so that we can keep the living / kitchen areas warm

Viktoria's studio

• what appears to be marked as a desk on the plan needs to be built-in floor to ceiling storage instead

Bathroom / Laundry

• we have decided to forgo having a shower-over-bath and just have a shower instead
• attached is a photo of a shower area we both love, and are hoping might be replicated to some extent (though probably not with a pebble floor) - it comes complete with built-in seating so that we can park our Zimmer frames in there when we are older

  

  Picture of a shower liked by Viktoria and the Android

Bedroom

• we are a little concerned that our large Victorian bed head won't be able to navigate the entry and around into the hallway - Viktoria re-measured the bed and at the centre it is 2330mm x 2130mm x 130mm. The posts at either corner are 1800mm high. Perhaps we need to have a sliding door in the main bedroom instead of a window so that we can get that big creature in? 

  

  Roof level plan with comments from Viktoria and the Android

  

The Android's Studio

• the Android is very happy with the rhomboid room-shape (apparently this makes for good acoustics)
• please omit the second sliding door to the concrete courtyard at the SE and replace with a high overhead window
• also add a window to the angled E wall (next to the stairs) - could this be a 'normal' window size?
• can the other window on the W wall be a high overhead window too
• and please include built-in floor-to-ceiling storage across the N wall (backing onto the carport)

Roof

• omit the courtyard off the Android's studio and convert to a roof instead
• where did our Greenroof go?

So that's where we left Neal... quite possibly scratching his head and muttering.
We'd love to know what you think - please leave a comment!

Visiting the architect's own home

During her lightning visit to Tasmania (ostensibly to choose a builder), Neal-the-architect also showed Viktoria around his own home (which, naturally, he had designed himself).
You can see on the JAWS website some photos taken of Neal's home during its construction here - although it's obviously in a far more advanced state of completion now than shown in these pictures.  And the photos really don't do it justice - it's quite a wonderful space to be in, with a logical sense of movement and pause, openness and enclosure.
Although it's constructed of robust materials (predominately bluestone block work and concrete) the curvilinear walls and integration of the bush setting lend the building a lightness and very human softness.
Viktoria cannot thank Neal and his family enough for making her feel so welcomed into their private home, and for the delicious barbecued Tasmanian salmon steaks we had for dinner. Mmmmmmm....
Actually, Viktoria ate like a king when she was there (yes, when Viktoria becomes king, even women will be allowed to be king).
If you are ever in the Hobart area and feeling hungry, we recommend stopping at Fish Frenzy at Elizabeth Street Pier, and trying the self-titled "Fish Frenzy" - a selection of blue-eye trevally, calamari and scallops with a generous serving of hot chips, wrapped up in a paper cone. It will feed one very hungry person, or two not-so-hungry people for AU $17.

The "Fish Frenzy" at Fish Frenzy

You can see from the reflection in the water in the photo above how beautiful and clear the weather was while she was there.
Viktoria stayed at Gattonside Heritage Accommodation in Battery Point which offered very reasonable winter rates - and was in very convenient walking distance to everything from the JAWS offices to Salamanca Markets and numerous coffee shops (as well as being in the beautiful historic Battery Point itself).


Gattonside in winter

Sadly, it will probably be some time before either Viktoria or the Android can return...

How to choose a builder

As mentioned earlier in this blog, the whole purpose of Viktoria making the lightning round-trip to Tasmania last week was to meet with, and hopefully choose, a builder. Neal-the-architect recommended that we get a builder involved in the project earlier on, due to the remote location and type of build.
As neither Viktoria nor the Android knew of any builders in Tasmania, Neal had short-listed three builders who were happy (or crazy enough) to agree to building on our site. This was a hugely wonderful thing for him to do, as a lot of the due diligence had already been carried out by the time Viktoria sat down with them. Again, we are running out of words to express our gratitude for all Neal has done.
Viktoria and the Android researched the three builders as much as possible from three States and a large stretch of water away, and decided that, much like choosing an architect, choosing a builder largely came down to who Viktoria thought she could get along with. And, as it would most likely be Viktoria and not the Android that the builder would be dealing with, it would also need to be the person that Viktoria thought would best be able to get along with her.

TIP: After researching previous projects & company history, choosing a builder is much like choosing an architect - it comes down to who you think you will be able to get along with when things go wrong.

Neal arranged for Viktoria and the builders to attend the JAWSarchitects offices in Battery Point. Donning his best "impartial mediator" guise, Neal would attend while Viktoria attempted to channel the universe to provide her with insight enough to make the correct decision.
Over two days, Viktoria met the builders, made lots of notes, and kept the Android updated. However, we knew it wasn't going to be a quick process, and we would have to sit down together before a decision was made. The process was drawn out because the Android had band rehearsals, Viktoria had to visit relatives, and both of us had to work.
Eventually, after many cups of tea and disjointed discussion, we picked Michael Lane from Cordwell Lane Building Pty Ltd, because:

• they had done a lot of block work before
• they had their own joiners
• they had their own glaziers
• they had worked on remote sites before

Viktoria also liked that Michael started thinking about how a revolving bookcase-secret doorway could be built, and didn't just make clever remarks about it.
So Corwell Lane Building it is. We have put together some pics of a few of their previous builds for you...

Cargo Bar; Paul Kelly Interior Design; Cordwell Lane Building

Basement; Preston Lane Architects; Cordwell Lane Building

Mt Pleasant addition; Cordwell Lane Building

Shearers' Quarters; John Wardle Architects; Cordwell Lane Building

The next things we need to do are:

• the Android needs to sort out getting the electricity connected to the site
• Viktoria will arrange for the geotec who did the initial soil tests to contact Neal to organise for some further testing on the final site
• we will collate our feedback on the second round of sketch designs for Neal (we will put these in the next post)
• Neal will arrange for the structural engineer to provide us with an idea of timing and costing for creating a rough driveway to the site

And that is where we are currently up to. When we have gathered our collective thoughts together, we will let you know how the house design is progressing and will post the latest sketch designs.