Location: Miami, Florida Property location: About two miles from Atlantic Ocean, soil is sandy. Property is single story, on monolithic concrete slab 8" thick. Via video inspection determine line is broken about 5 feet inside from an exterior wall probably directly under a cabinet in the kitchen, with no replacement tiles available. The line is broken near an elbow so using a resin liner solution is out. Had another plumber came by but he thinks he will need to open up a hole 48"x48" under the cabinets. He will have to use a large wet saw to cut the hole under and probably will damage the cabinets, and with a lot of mess, and that will be $1800 as well, plus patching the concrete slab, plus redoing some cabinets, and new tile work. Plus if they work inside one of us has to take time off to be at home, a two day off will also end up costing us additional money.
Had two drain companies came out and both recommend tunnel under house.
Roto-Rooter estimated $1800 excavation + $900 pipe repair. The $1800 excavation cost is based on a $180 per foot basis. Since the location is around 5 feet in, they figured 4 feet deep, 5 feet in, and an extra foot for manuever will add to 10 feet. However, if there is a footing to cause them to dig deeper than originally thought (I am pretty sure there is), or they hit the water table (yes they probably will...) or the location is not pinned down and they have to dig further to find the break (and that may happen too...), it will be however long they dig times $180. So I figure conservative estimate will be to figure 20 feet, which will mean $3600 + $900 = $4500. I asked them how they will back fill and they told me they will put the original dirt back in and it should be OK. The digging will be done manually. They did not say whether there will be any permit fee or whether they will get a permit or not.
The AAA Rapid Rooter came by, and their estimate is totally different. They told me their charge is $7500 minimum. Minimum meaning they don't run into complications. I asked them what they included, and they told me it included using a "vaccon" truck to dig the tunnel (not manual digging), they add water and literally "suck" the sand out and form the tunnel, the actual pipe repair, permit fee, engineer to come out to see the soil sample is suitable for excavation of this nature, backfill with a truck shooting wet sand (may mix some cement in) into the tunnel. The total will be $7500. They will not provide an itemized breakdown since some clients used their estimate to get insurance money but never do the job.
So drastically different approach. Machine digging with water versus manual digging. Manual backfill with excavated dirt versus shooting compacted sand. One job is about twice as the other.
Any idea which one is more "safe and sound"? I have the feeling manual digging is less damaging and involve less disturbance to the soil and can keep the tunnel size smallest, is this right? But backfilling with the original dirt concerns me. Not sure how you can backfill the void that is above the footing back without some sort of pressurized method. Both are reputable companies.
I am thinking one possibility would be to use Roto-Rooter to do the repair, and see if they will come down on the price if I ask them NOT to back fill. I will back fill myself and see if I can find a subcontractor that will do the wet sand shooting back fill. But will this work? They can't pull the permit if I am going to do part of the work myself?
I am interested to know: Which approach is better and safer?