Loleta Elementary rainwater

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Engr305 Appropriate Technology page in progress
This page is a project in progress by students in Engr305 Appropriate Technology. Please do not make edits unless you are a member of the team working on this page, but feel free to make comments on the discussion page. Check back for the finished version on May 15, 2018.


Background[edit]

Loleta Elementary School offers its students a garden that is cared for by onsite staff. The school plans to also add a small fruit orchard in the near future. When the fall season arrives, the school offers the community a pumpkin patch, effectively generating an additional source of revenue. Both of these agricultural activities require continued irrigation. Rather than having irrigation water provided by the municipality, Loleta Elementary School wishes to install a rainwater catchment system to support their irrigation needs.

Problem statement[edit]

The objective of this project is to install a rainwater catchment system that will reduce the cost of irrigating the garden and pumpkin patch.

Project Evaluation Criteria[edit]

The following Criteria will be used to assess the success of this project. These criteria were chosen by the team and staff members from Loleta Elementary. The scale (1-10) represents the importance level of meeting the constraint of each listed criteria.

Criteria Constraints Weight
(1-10)
Safety Will not cause a danger to students or staff.
10
Functionality/Effectiveness Must provide enough rainwater to the garden to grow food for the school and drastically reduce the schools water bill.
10
Adaptability Be able to be modified if needed. Be able to build off of to install a water bottle filling station in the future.
7
Cost Supplies and materials must cost less than $1,000 US dollars.
2
Maintainability Be able to be kept in good condition by the experienced grounds keeper
5
Durability Be able to last several years with general cleaning and maintenance
8

Literature Review[edit]

This is a review of the available literature pertinent to our project.

Local Climate[edit]

Annual Normal Precipitation for Loleta and the surrounding Region[1]

The average precipitation of Loleta ranges between 40 in. to 50 in. annually. [1] On average, Loleta experiences rainfall events of more than 0.1 inches approximately 89.1 days out of the year. On the contrary, Loleta experiences 177 days that are predominately sunny. [2]

Material Components[edit]

Conveyance–  carries water from roof catchment area to storage tank (in the case of a “built” system), or directly to the ground area where the water will be used (in the case of “natural” systems) . Conveyance components include, generally, gutters and downspouts. The most common and affordable Gutters/downspout materials are made of: bamboo, galvanized sheet metal, or PVC (either intact or cut in half). 

(Grafman, 16, 2017). Material appropriateness varies based on the type of system, availability, affordability, and aesthetic considerations. It’s also important to consider the Social, economic, and environmental aspects of the circumstances under which the system is being installed. ( Gould, 1999)

Storage

Storage tanks vary in size and material composition, and choice of storage tank depends upon catchment potential of roof surface, and the specific use of the water. Types of storage containers for built systems include: Plastic storage tanks, Commercial rainwater tanks, 55-gallon drums, Ferrocement tanks (made of cement or lime mixed with sand, applied over metal mesh), and intermediate bulk containers (Grafman, 16-18, 2017). Determining Daily maximum precipitation is a key factor in determining what types of materials to use and what size tank to install, to be sure that the system doesn’t become damaged or overloaded. (Yi Li et al, 2018). ref>Kinkade-Levario, Heather. Design for Water : Rainwater Harvesting, Stormwater Catchment, and Alternate Water Reuse, New Society Publishers, 2007. ProQuest Ebook Central, https://ebookcentral.proquest.com/lib/humboldt/detail.action?docID=316343.</ref> ref>Gould, J., & Nissen-Petersen, E. (1999). Rainwater catchment systems for domestic supply: Design, construction and implementation. London: Intermediate Technology Publications.</ref> ref>Li et al., “Multi-Objective Optimization Integrated with Life Cycle Assessment for Rainwater Harvesting Systems.” </ref>

Roofing Materials[edit]

Rainwater catchment surfaces can include thatch, tile, corrugated metal, asphalt, concrete, standing seam metal. Catchment efficiency depends on roofing material, with corrugated metal and standing seam metal being the most efficient (approx. 95% efficiency) and thatch and tile being the least efficient. Water safety also varies based upon roofing material, with asphalt and thatch being lowest safety and tile and standing seam metal being highest. The safety of corrugated metal varies based on coating. (Grafman 8, 2017). Copper roofs are not suitable for rainwater collection. Likewise, galvanized steel, which contains zinc, is not suited for rainwater collection. (Kinkade-Levario, 2007)

Local Governance & Planning[edit]

Loleta is not an incorporated city, therefore all development is regulated by Humboldt County Planning and Building Department. Developing water storage structures requires permits from local agencies depending on the size and scale. Water storage structures that exceed 5,000 gallons require a permit from the Humbodlt County Building Inspection Division.[3] Fees and payments associated with the required permit varies depending on the storage size, number of referral agencies, and total number of permits. [4]

Building Permits[edit]

Water storage structures that exceed 5,000 gallons require a permit from the Humbodlt County Building Inspection Division. Building Permits may take approximately 4 to 6 weeks to get approved.[3]

Conditional Use Permits[edit]

If the water storage structure exceeds 50,000 gallons, than a Conditional Use Permit from the Humboldt County Planning Division but be acquired. A Conditional Use Permit may take approximately 4 to 6 months to get approved.[3]

Gravity Fed Irrigation[edit]

Water Filtration[edit]

Different components will remove debris and initial pollution from the rainwater. Having a screen in place will separate debris from the water and having a first flush system will remove the dirtiest water from going to the storage tank (Grafman, 2017). By removing more containments before the water gets to the storage tank, the easier it will be to maintain and clean the tank[5] (Allen Novak, 2014). If the end use will be drinking water, however, more filtration will be needed.

Filtration Type 1- Chlorine:[edit]

Chlorine can be used to kill a wide range of disease causing organisms in water. It is commonly used but can be hazardous at certain levels and even at safe levels, leave a taste in the water (Grafman, 2017).

Filtration Type 2 – Slow-sand filters[edit]

A layer of biological material, Schmutzdeck, on top of layers of sand and gravel. This method takes longer to filter water but is a good option for projects with smaller budgets and can be used for drinking (Grafman, 2017).
  1. 1.0 1.1 http://water.weather.gov/precip/#
  2. https://www.bestplaces.net/climate/city/california/loleta
  3. 3.0 3.1 3.2 https://humboldtgov.org/documentcenter/view/6565
  4. http://humboldtgov.org/documentcenter/view/51632
  5. https://ebookcentral.proquest.com/lib/humboldt/reader.action?docID=1650821&query=