Preparation

Does this sight seems familiar?  It might be a replay of the excavation from summer 2012.  On Thursday 9/20, contractor Harold Anderson began the process of replacing our septic system using a backhoe-loader, which is an optimal machine for our tight space.  He and his son, Jeremy at right, are beginning the process of excavating our old tank for a new system.

Old Out

The old, 50-year-old tank had hundreds of perforations. Removing that defective tank required another pump out.  In this same location will be a new, larger concrete septic tank.  Our intention was to maintain our existing leech field.

Excavation

The plan was to essentially "swap out" the old tank for a new version.  This system would hopefully not become a holding tank, requiring pump-outs twice a year.
Excavating into the sandy pit was unstable, and cave-ins of the wall edges were recurrent.  The water table was evident at the bottom.

Level

Making the base for the new tank into a perfectly level platform was essential.  Pea gravel was shoveled into the bottom for support.  Our contractor's son, Jeremy, did the tough, dirty work of standing in the muck and standing water, and developing it all into a supportive, level base. 

 

Delivery

Knuckle boom crane was used for delivery.  The new septic tank has a 1,000 gallon capacity;  as delivered, it weighs about 8,500 pounds.  This truck needed to be backed down our steep driveway and bring the knuckle boom close to the site.  Although this tool is very contemporary, and extremely helpful in tight spots, the operator is a crucial element.

Our cottage represents a tight spot.

Placing

Placing the tank was complex.  Trees were intrusive, driveway was awkward, space was tight.  Anxiety was high.  Warnings and stories bubbled up about prior problems:  e.g: broken cables, cracked concrete, dropped tanks, and the inability to place the tank "just right."  The immediate concern would be whether a prolonged revision of the tank placement might be required.

After two tries, the tank seated well: it was in alignment with the existing piping, it was level and it fit in the excavation.  The delivery and placement were really quite impressive.

A bit high . . . .

OK, the tank is level, and OK, it has an appropriately minimal pitch away from the cottage.  However, being seated about 3-4 inches deeper would have been optimal.  But we can't complain:  it all works!

In this picture, the tank aspect nearest the lake is even with the lawn, and the aspect nearest the woods is  5"-6" below grade.  Overall, this is just a bit high for the grade of the lawn. So the net result is that the turn in the driveway will need to be a bit higher than the original, with more pitch toward the grass and lawn.

Install Pipe

Because the tank was seated a bit high, a readjustment of the drain pipe from house to tank was necessary.  Good news is that the tank "swap out" means that we are not a holding tank, but remain a functional system.  Our outflow pipe is very slow, but adequate.  We will likely need an adjustment of our leach field out-piping in the spring.  More later.

Driveway Regrading

Regrading the driveway with a crusher run gravel is intended to make a more solid surface for our steep incline.  Hopefully, compactable coarse aggregate will 'winter over' and in 2013 should hopefully solidify into a better surface.