Contractor’s Notes; Greywater and Rainwater Harvesting
Rainwater Catchment Pond Plan
Huasna Valley averages 20 inches of rainfall annually. In other words every drop counts. When looking at the water use for this project we wanted to ensure that we were being responsible with the water that would be used. The two areas we focused on were Rainwater Harvesting and Greywater systems to provide water for landscaping features and irrigation.
Recently California and San Luis Obispo County have loosened their regulations for using Greywater. Working with Michael Robertson of Green Goods (www.slogreengoods.com) we calculated the amount of Greywater that could be diverted from the septic system and used for landscaping. Michael provided the gallons per day diversion. The Civil Engineer took these figures and was able to reduce the size of the leech field, in our case by about 30%. This meant that the money saved in installing the extra leech lines could be used to pay for labor and materials to install the new Greywater system. Now we will be using less potable water to irrigate landscaping and reduce the area of disturbance of natural pasture due to a smaller leech field. Michael Robertson also provided the plumbing subcontractor with line drawings and a materials list so that even plumbers with little to no Greywater experience could install a simple system.
For this project at the Grooms Quarters which is a 2 bedroom, 1 bath, single family residence we were able to divert Greywater from two vanities, one shower and the washing machine. At the Stables we were able to divert water from two vanities and a washing machine. We decided to go with a very low tech, low maintenance system in which the exiting Greywater will go to a mulch pit that will supply enough water for several medium sized trees. Also water used for washing the horses and stalls will be collected in drainage pipes which will supply water to landscaping in the courtyard of the Stables. Costs do increase if you plan to use more advanced irrigation, drip systems for example. Still as the cost of water increase, either from a utility bill or the cost of energy to pull it from a well, the cost of installing a Greywater System can make financial sense as well as conserving potable water. For more information on Greywater go to http://slogreenbuild.org/Library/documents/general/Graywater_08_20_09.pdf .
Next we looked at Rainwater Harvesting for use in landscaping. We have over 15,000 sq. ft. of roof area from the Hay Barn/Grooms Quarters, Stables and covered riding Arena. I started by visiting the NRCS offices in Templeton and spoke at length with Susan Litteral who is passionate about water conservation and has a wealth of knowledge on the subject. The NRCS is a federal agency that provides free information/consultation to agricultural businesses primarily and time permitting anyone who wishes to integrate conservation into their property. She suggested we have our civil engineer calculate the amount of rainwater to be harvested and design a “holding pond” that would meet NRCS standards. They could then sign off on the design and we could build the holding pond to these specifications. As it turns out with our project we will be under one acre foot of water that needs to be stored. This meant we did not need to get NRCS approval or a county permit because the lots are zoned Agricultural. We now have the design for the catchment pond and placed it on the property. Now we are just waiting for things to dry out from all the rain we have been having and we will start excavation. For more information on Rainwater Harvesting visit http://www.harvestingrainwater.com/.
-Frank Cullen; President; Cullen Construction, Inc.
