When I discuss leveling of an existing tee box with a client I bring a shovel and a laser. I identify the elevation of each corner then I calculate the current slope. If it’s an even 1%, the tee resurfacing will require little grading. If not, the contractor must perform significant grading to construct a flat tee surface at a uniform 1%.
When altering existing tee slopes, tee mix depth will be a concern. I’ll dig small test holes on each tee corner. I’ll set the laser on 1% on my intended slope and direction then place the end of the rod in each shovel hole. This will identify the tee mix depth after the grading.
If I see a good six inches of tee mix, I can perform my grade change without any problems. If I am tee mix deficient, I’ll change the specifications to include plating the entire tee platform with a compatible tee mix. Plate the tee pad with sand if the existing tee mix is loamy. To insure tee mix uniformity, we usually blend the old and new tee mixes with a tiller.
Tee root zone mix installation involves careful planning and execution to limit subsurface drainage impacts while insuring even compaction.
I’ve seen a few contractors ruin subsurface grading and drainage piping by jamming tee rootzone mix without any concern for tee subgrades and piping. They try to increase production by doing the following:
Driving a truck or trailer over the tee subgrade (the surface under the tee mix). Good construction methods incorporate the tee surface slope into the subgrade because this allows a true mirror image of the tee top slope while insuring positive subsurface water flow. A tire track or two will disrupt this sheet flow and crunch the drainage pipes. Note: we always install subsurface pipes under tee mix.
Plowing out the tee mix with a bulldozer without any compaction technique.
We use these methods to install mix:
Establish subgrade and finish grade stakes on the four tee corners (assuming you want a square tee). Calculate the amount of tee mix needed and transport this volume to the edge of the new tee. Stack the mix in a big pile on the edge of the tee. Don’t drive a truck or trailer over the tee edge. When the pile is complete, plow out a few inch lift of tee mix over the subgrade floor.
Plow out another lift ( a lift is an even spread of soil i.e. a six inch lift) or two to establish design depth. This process creates even compaction-the dozer or excavator tracks do a nice job with this.
Run a few strings connecting the four corners, and add or subtract mix as needed.