2. Insert Your Fill Tubes
Now that your liner is in place, you will need to cut a hole in one of the two pipes per box. This hole will then be filled with a PVC coupler, so be sure to make the hole the appropriate size. You can use the silver marker to indicate on the piping where you need to cut. After the coupler is in place, you can cut your PVC pipe to be about half an inch above the top of the box, put the PVC cap on and then insert the pipe into the coupler as shown above.
Special note: if these boxes are going to be placed in an area that gets a lot of rain, it will be necessary to drill a drainage hole into one side of each box. Place the hole in the void of one of the corrugated pipes, approximately ¾ of the way up the pipe in question. You will also need to waterproof the inside section of the box where the hole is drilled.