Black hole secondary overview.jpg
FA info icon.svg Angle down icon.svg Project data
Type Rainwater catchment
Authors Jenna Davey
Karen Duarte
Richard Thompson
Caleb Wegner
Location Arcata, California
Status Deployed
Years 2016
Cost USD 83.88
OKH Manifest Download

A rainwater catchment system was designed and constructed at The Sanctuary in Arcata, CA. This project was completed for Cal Poly Humboldt class, ENGR 215 FALL 16, and is a collaboration between four students: Jenna Davey, Karen Duarte, Richard Thompson, and Caleb Wegener. The catchment system can hold up to 900 gallons of captured rainwater. A 55 gallon drum is used as the secondary storage. A 850 gallon pond acts as the primary storage for the system. The pond is covered with a bridge, for walking or storage, and the pond contains an overflow drain.

Background[edit | edit source]

Sacred Consulting is a team of four students in the Fall 2016 semester of ENGR 215 at Cal Poly Humboldt consists of: Jenna Davey, Karen Duarte, Richard Thompson, and Caleb Wegner. This group chose to design and construct a rainwater catchment system for the client. The client for this project is The Creative Sanctuary, a local non-profit art facility who promotes green technology, art, community involvement and sustainable living. Even though this client has one rainwater catchment system on the property already, there are 2 gutters currently not being used for collection.

Problem statement and criteria[edit | edit source]

Criteria and constraints are a set of useful guidelines to refer to when deciding which design best fits the needs of the client.

Problem Statement[edit | edit source]

The Creative Sanctuary has two rain gutters that are not being used to collect the water, and would like to use one or both of them as inputs to a rainwater catchment system.

Criteria[edit | edit source]

Below is a table that displays the criteria laid out to assist in the decision making process.

Criteria Importance Constraints
Sustainability 9 Obtain the lowest embedded energy for each item in the system.
Cost 8 Spend less than $400.
Usefulness 8 Storage capacity must provide at least 25% of the water for the garden and other outdoor uses.
Maintenance 8 Maintenance must require less than 1hr per week.
Aesthetics 7 look as good or better than the surrounding structures.
Accessibility 5 The area must still be available to foot traffic.
Sizing 4 Water storage must match the volume of the water coming into the system.

Description of final project[edit | edit source]

Photos and descriptions.

Cost Table[edit | edit source]

The costs in hours for this project are listed below. The total hours spent by the team both designing and implementing the system is 150 hrs.

The monetary costs of this project are minimal considering the amount of donated materials which came from the client, The Sanctuary. The total cost of the system is $83.88 and a breakdown of the cost of each item can be seen below.

Quantity Material Source Cost ($) Total ($)
1 15' x 15' Black Pond Liner Donated 0.00 0.00
13 ft. 2" Black ABS Pipe Donated 0.00 0.00
32 ft. 3" Black Corrugated Drain Pipe Donated 0.00 0.00
1 55 gallon Blue PVC barrel w/ White Lid Donated 0.00 0.00
1 3" Black Corrugated Drain Elbow Fitting Donated 0.00 0.00
1 1/2 Plastic Tubing Donated 0.00 0.00
179" 3" Black ABS Pipe Donated 0.00 0.00
ABS Adhesive Donated 0.00 0.00
ABS Primer Donated 0.00 0.00
3 3" ABS Tee Fitting Ace Hardware 7.99 23.97
6 3" ABS 90 (degrees) Elbow Fitting Ace Hardware 6.99 41.94
1 2" Adapter Ace Hardware 1.99 1.99
2 3" to 2" Couple flex Fitting Ace Hardware 7.99 15.98
Total Cost $83.88

Testing Results[edit | edit source]

The system is currently filling up and storing water, but has not had the chance to provide water to the garden because the rain has been sufficient enough up to this point in time.

How to build[edit | edit source]

In order to replicate the rainwater catchment system that was built for the Sanctuary, follow the steps below. YOU WILL NEED A SHOVEL.


Dig a 7x6x5 hole. (or the dimensions of the hole you would like.)


Dig a shallow trench extending from a side of the pond with the lowest walls and heating downhill is necessary for the overflow drain. Any other necessary trenches can be dug at this time. ( take into consideration the placement of a first flush diverter and a secondary storage.


Installing first fish diverter (you can use a 20 gallon barrel)


First flush diverter and Secondary storage need to be fitted to their respected outlet. for the first flush, this will be a very small drain placed about one-third of the way up the barrel, allowing the sediment to fall to the bottom of the tank without clogging the drain.


Create a secure foundation for the first flush diverter and secondary storage. It is suggested to put some type of concrete or very solid base under these storage units.


Installation of First flush diverter and secondary storage should be complete.


Layout carpet in the hole to protect from any sharp objects and place pond liner into the hole.


Next, use pipes to link the gutters to the rainwater catchment system.(Piped need to be "dry-fitted." )


Use a permanent marker to number each connection and also mark a line to use for lining up the angles on each of the connections.


Start priming and gluing the pipes together. Be careful to only glue the sections that can be installed as once piece because all of the connections will now be permanently in place.


Place the glued pipe sections into the trenches.


Place the over flow drain pipe through the pond liner.


Make sure all your sections are secured, glued, and connected.


Congratulations the system is now installed and ready to be tested.


Maintenance[edit | edit source]

"The Black Hole" was designed to need as little regular maintenance as possible. Due to this there is only an estimated 7 hours per year in required maintenance. The breakdown of what tasks need to be done and the estimated cost are shown below.

Schedule[edit | edit source]

Every year the system needs a complete cleaning and winterization. This annual cleaning should be performed in the fall of the year before the rains start. This allows the system to be as clean as possible before filling with water. If the entire system needs to be cleaned and the pond is full of water, that water must be emptied so that the pond liner can be removed to be cleaned. While the total cleaning time can vary, cleaning the pond liner should only take one hour if all the water has been removed.

The other task that will need to be completed is the emptying and cleaning of the first flush water diverter and the secondary tank. Occasionally, this first flush diverter will become clogged with debris and sediment. Time needed to empty and clean the first flush water diverter and secondary storage is estimated to take less than one half of an hour. This maintenance is recommended to be performed once a month.

In total the system should require under 7 hours of maintenance per year.

  • Empty and clean secondary storage
  • Empty and clean first flush diverter
  • Remove/Clean/Replace pond liner
  • Flush all pipes and clean gutters

Troubleshooting[edit | edit source]

This is only how to troubleshoot basic operation. For complex issues, contact Lonny Grafman (HSU).

Problem Suggestion
Water is not flowing into the pond. Check flow by putting a hose into the gutter and find clogged area.
Water is dirty. First flush diverter is not draining properly.
Pond wall integrity Too much water in area surrounding the pond.

Discussion and next steps[edit | edit source]

References[edit | edit source]

Poster[edit | edit source]

Rainwater Catchment Poster 1.jpg

Update October 2017[edit | edit source]

Interviewed Natalie about how the the catchment system is doing. Overall health of the system is great, everything from the first flush to the storage. Currently using the water for watering plants in the garden. The system is doing great and satisfying their current needs; a future system is not currently on their radar.

A photo of the "black hole" storage in October 2017.

The Black Hole Storage 1.jpg

Update September 2018[edit | edit source]

Katie was interviewed about the system, she gave us some updates:

Katie and rainwater system.png

  • Still being used to water garden
  • Would like to use the system for other purposes in the future.
  • The system has a broken valve, the valve needs to be replaced with a new one, preferably metal.

Rainwater sanctuary 2018.png

  • Would like a better way of getting water from the system, aside from opening the porthole- not very user friendly.
  • In need of signage/reminder to maintain.

Update September 2019[edit | edit source]

The rainwater catchment system appeared to be fully functioning. When asked if there were noticeable changes in the water bill, there didn't appear to be however, Katie responded with "the plants look so much healthier." As for maintenance there didn't appear to be much. The valve that was used to release the first flush had chipped and could not be moved unless with a wrench. In the dry season fish are used as a means to reduce mosquitos. For the first time since its conception a small animal fell into the tank and sadly died which then emitted a smell. Thankfully the water is only used for the plants. There was also talk of expanding the system. All in all the catchment system was a success.

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