My basement is unfinished and below grade. I have 2 cracks, one hairline where the septic pipe goes throught the wall (about 3' below grade)and one along a 90 degree angle section where the basement stairwell meets the main house (originally a continuous pour for the two sections) that runs from top to bottom, 1/8" wide at top to hairline at the bottom. I have investigated several options - dig up and seal with yd. cement and cover with roofing tar and plastic, hydrophobic polyurethane injection, and interior drain tile. wat do you recommend as the best solution?