Well, the R-Tank is doing it's job... before it's even built

We dug a hole in preparation for a new Brentwood R-TANK system for a developer. 

Unfortunately, the hole is already filling with water, having just been dug. It's also located on the lowest side of the property (natural gravity drainage). It also has a stream that goes right through the project, which virtually changes 1 project, into 2, since you cannot just bulldoze through wetlands/streams. 

For those unfamiliar, R-TANKs is an onsite retention system for storm water, to slowly seep out into the mainline, preventing long-term flooding downstream, and premature failure of complex storm systems.

There truly is a lot more than just a bunch of pipes with drain grates.

Below, I've included some more pictures of the R-TANK being assembled. 

This is our work area, once the water was pumped out.
We laid down the landscaping fabric over a level gravel bed, so the vinyl liner stays safe from puncturing. 

This specific tank was 2 tall, once the crates are built and placed in (vertically attached with gravity, and 2 plastic pins to keep alignment, but do not attach to each other). 
Once the shape of the tank is built with crates, you line the vinyl & fabric up the sides, and that creates your tank space. Some R-TANKs have a vinyl top that is glued to the sides to hold them, some of them are open for surface drainage.