CCAT greywater marsh (2008): Difference between revisions

Introduction

History

Greywater is the water from your sink, shower and washing machine(everything but the toilet) that goes down your drain to the treatment plant. This water can be filtered and then used to water plants in your own backyard (see the general Greywater page for more info). The Campus Center for Appropriate Technology (CCAT) has had plans to build a new greywater treatment marsh since the CCAT house (yes, the actual house) was moved a few years ago, changing the layout of the yard. As our project for Engineering 305 class ("Appropriate Technology"), we decided that making this plan a reality would be an appropriate use of our time and energy that many people could continue to learn from for years.

Description

• Greywater Outlet

During renovation of the CCAT house, plumbing was designed to divert greywater from blackwater; making it easier for the future greywater project. This outlet is located 3' beneath the ground.

• Sedimentation Basin

The basin is composed of a 50 gallon drum which was acquired through the Campus Recycling Program. It is located directly next to the outlet, the top of the 3' barrel is 2' below ground level.

• Pipe to Marsh

A 27' long, 2" wide pipe was needed to pipe the water from the Sedimentation Basin to the Surge Tank. The reason why these two components are so far apart is because a driveway needed to be built between the outlet and the marsh site.

• Surge Tank

A Surge tank was included in the design of this system to provide protection from overflow. The tank itself serves as a place for the untreated water to go if a large amount of water flows out of the house all at once. Surge capacity. how much? gallon?

• Gravel Marsh

The actual treatment area is 4' wide by 14' long by 3' deep. Because this system was built on a hill, we had to dig even deeper than 3' to make up for the slope. We decided that 2 lower baffles and 3 upper baffles would suit our treatment needs. The baffles are barriers that direct water flow and maximize surface area therefore maximizing the amount of treatment in the given area.

Construction

Detail

• Diverting Greywater

We started by digging a hole 5' deep by the greywater outlet for the sedimentation basin to sit in. The 3' tall, 50 gallon basin rests in the bottom.

• From the House to the Marsh

After this, we dug the trench from the outlet to the marsh location. The trench was 3' deep and 27' feet long. The trench was started during the previous semester. Don't underestimate how long it takes to dig by hand.

• Extra Plumbing

We placed 2" piping inside a 4" sleeve in the trench. The sleeve was required by HSU Plant Operations because a driveway needed to be built over it.

• The Big Hole

We marked the shape of the marsh and the hole for the surge tank (located between the trench and the marsh itself), and started digging. To accommodate the calculated flow from the house, we needed a marsh 10' long, 4' wide and 3' deep. (INSERT DETAILS ABOUT FLOW) We decided that based on the slope of the adjacent hill, we would need to dig a hole 5' deep in order to have a marsh 3' deep.

• Baffles? Baffles!

We cut out baffles made of plywood and hardwood to about 4' wide, 2.5' high and lined the 3 top baffles with pond liner in hopes of delaying decay. We installed the bottom two by wedging them in the dirt.

• Pond Liner

At our local landscaping store, we purchased a 23' x 10' cut of pond liner. We calculated this size by figuring the area of the marsh walls plus the area of the two bottom baffles, and an extra foot on all sides (it might be a good idea to calculate an extra 2' on all sides as the liner shifts when you start filling it with gravel). It was helpful to tack the edge of the liner into the ground when filling it. After the liner was in, the 3 top baffles were installed; one a foot from the marsh inlet, one a foot from the marsh outlet, and one smack in the middle of the two bottom baffles. the bottom of the top baffles were placed approximately 6" from the marsh floor.

• Gravel

We started the task of filling the marsh with gravel by holding the upper baffles in place while another person shoveled/dumped gravel into it. It is very important to pay attention to your pond liner height on all sides as you are filling! We left about a foot of room at the top before we started planting.

• Planting

Bulrush, a marshy plant that loves filtering greywater, was found at local marshy areas. We planted these straight into the gravel, at 1' and 6" from the top. We planted approximately 30 plants, dispersed from the 1st upper baffle to the outlet. We watered these thirsty plants after transplant and will continue to whenever they look dry until the greywater starts flowing form the house.

• Sedimentation Basin installation

• Surge Tank installation

• End use

The greywater crew and CCAT authorities agreed that the end use of the treated greywater deserved to be a project in itself, with as much thought and planning as went into the greywater treatment alone. To be continued...

Plans

Maintenance and Testing

Future Projects

Vision

Special Thanks

Special thanks goes out to all of the lovely volunteers we had at CCAT every Friday, the CCAT Co-D's for being so patient and supportive, everyone who helped with the design and construction of this here marsh, Nathan Chase, the Engineering 305 class, Miller Farms, HSU Plant Operations, thanks to bulrushes, wheelbarrows, shovels, rice, chocolate and water. This project simply couldn't have been possible without this wonderful, supportive community.