Septic tank lids can be very expensive when it comes time to replace one. Most minor repairs on a concrete septic tank lid can be done relatively easy without having to replace the whole lid. Concrete septic tank lids tend to crack and break after years of being exposed to the elements and constant moisture coming from below the lid. The concrete lids will generally crack and break in small areas and if you can repair them as soon as possible, then you can actually salvage the concrete septic tank lid.
Take a flat head screwdriver and start scraping out the cranks in the concrete septic tank lid. Scrape out as much of the sand and debris as you can with the screwdriver.
Take a wire brush and brush the sand and debris out of the cracks. Continue brushing out the cracks until the crack is clean and smooth.
Wash out the cracks with water from a hose and let the cracks completely dry.
Open up a "Concrete Epoxy Crack Filler Kit" and mix the ingredients as directed on the kit in a clean bucket. The kit will call for sand and water, so have a little bit of sand handy. You can add the accompaning drill attachment to mix the sand into the epoxy filler.
Add the fresh concrete epoxy crack filler to the trowel and start spreading the filler into the cracks very thoroughly. Put pressure on the trowel when applying the epoxy filler to the cracks so that the filler will go deep into the cracks.
Smooth the filler out into the existing concrete and then let the filler completely dry. The amount of drying time for the epoxy filler will be on the kit. Once the filler has completely dried into the concrete crack, the newly repaired crack will actually be stronger than the concrete itself.
Add the epoxy filler soon after mixing the kit ingredients together, because the epoxy will start to bond with the hardener and start to harden very quickly. The epoxy filler will actually make the crack and the concrete around the crack stronger than the existing cracks.
Wear safety glasses and protective gloves when mixing epoxy to prevent minor chemical burns.