open foundation slab under bath-tub

Good afternoon.

I have removed a gardener roofing tar in the main bath-tub foundation drain that has to be left open due to City code for the Plumbers (in case of future issues/repair. They use the roofing tar as a non-permeable damp-proofing purpose for the soil and PVC drain pipe, including termite barrier.

I removed the roofing tar as their damp-proofing due to high VOC (toxicology) report including carcinogenic effects.

Is their a eco-friendly, or non-VOC water soluble or any other solution I can buy to poor in our 12” open foundation, which is within the wall and non-vented exterior, where the bath tube down spout drains?
Maybe: tank-slurry, or polyurathane foam?