Constructing a High Tunnel on Your Farm

High Tunnel Bows

Constructed high tunnel bows

CFSA’s Lomax Farm was awarded an NRCS-EQIP contract for a high tunnel through the High Tunnel Systems Initiative. Construction began during CFSA’s High Tunnel Construction Field Day at Lomax Farm on October 3, 2017.

The Lomax Farm staff documented the process, from applying for the NRCS grant to beginning construction of the high tunnel. If you are thinking about applying for funding for an NRCS-EQIP high tunnel, here is what you need to know.

Before you apply:

  • Obtain a Farm Services Agency (FSA) Farm ID. Because NRCS is a USDA-funded entity, you must register your farm with FSA and get a farm number. This will put your farm in the FSA system and make you eligible for federal funding, including other federal programs such as farm loans, crop insurance, and disaster compensation.
  • Contact your local NRCS area office. These offices often serve multiple counties, so check to see which office serves your county for North Carolina and South Carolina. Your local NRCS agent will be able to answer questions specific to your area.
  • Check if you are eligible. The High Tunnel Systems Initiative is for established growers to assist with season extension on land capable of growing crops. An area agent will come out to your farm for a site check and evaluate your eligibility, including whether you are already producing crops and if the land is appropriate for a high tunnel system.

 

Applying

Each state has different deadlines for applying. For North Carolina, the next deadline to apply for funding is November 17, 2017. For South Carolina the deadline is November 18, 2017.

 

Funding

Currently, NRCS will fund up to a maximum of 2,178 square feet of high tunnel space, which is roughly the size of a 30’x72’ tunnel. This means that if you apply for funding for a larger 30’x96’ tunnel, you are expected to pay the difference. However, if you receive funding for a smaller tunnel, you may apply for more funding in future years for another small tunnel, up to a lifetime maximum of 2,178 square feet.

 

Site Visit

When you are approved for funding, an NRCS agent will conduct a site visit and will work with you to choose the best location for the tunnel. The location of the tunnel will be based on a number of considerations, including proximity to viable irrigation, erosion potential, solar access, and topography. The location that is decided upon with input from your NRCS agent must be the final placement of the tunnel.

 

Choosing Your High Tunnel

The high tunnel must meet NRCS standards. This is usually not an issue and many manufacturers are already familiar with the guidelines. While you can select from a variety of high tunnels, NRCS requires that the tunnel be a manufactured kit, constructed to the manufacturer’s recommendations. The kits must also have a four-year warranty, and once constructed the tunnel must remain as it was originally designed for four years. This does not include adding enhancements, such as gutters or a rain catchment system.

 

Purchasing

Once the application has been approved and the contract is signed, you can purchase your high tunnel. You have one year from the time of signing the contract to construct your tunnel, and you will receive reimbursement only after the construction is complete and a site visit is made.

 

Once constructed, the high tunnel serves only to grow crops in the native soil within the tunnel, meaning hydroponic systems, portable grow containers, and raised beds over 12” tall are excluded. Additionally, the high tunnel may not be used to house livestock, or store equipment, farm supplies, hay or other feed.

 

What to Expect When You’re Expecting a High Tunnel

 

Ground Preparation

When you choose a site for the tunnel, even the most ideal location might require some grading work. The ground should be as level as possible to ensure proper construction, and to minimize erosion and water runoff. Unless you have the proper equipment such as a skid steer or tractor with a bucket attachment, grader blade, land leveler, or box blade, plan to contract this work and budget an extra $500-$1,000. Also consider where your high tunnel is in relation to your other fields, and whether you will need to install a diversion ditch or soil conservation swale.

 

Finished Graded Pad

Finished Graded Pad

 

Delivery

Depending on what model you order and what manufacturer you order it from, the packaging and freight will vary. Remember to budget in the cost of shipping, which could be upwards of $1,500 for larger tunnels.

 

It is critical that you have the right equipment and tools for unloading the pieces to maintain your personal safety and to minimize damage to the high tunnel. The tunnel will most likely be delivered on a tractor-trailer, strapped to pallets at the back of the container. On the day the high tunnel arrives, make sure you are ready to receive it with the following:

  • Tractor or skid steer with forks. If the pieces arrive on pallets, the easiest way to unload the tunnel is with forks, as long as the tractor has enough horsepower and weight behind it so as not to tip.
  • Pallet jack. If unloading or re-stacking by hand.
  • Bolt cutters. Some pieces might be wrapped together with steel strapping and will need to be cut before unloading.
  • Gloves and sturdy shoes. The metal pieces are sharp and heavy.
  • Plenty of time. Budget at least an hour for unloading, even if you have extra hands to help out.

 

 

Inventory

After unloading, take inventory of all the pieces to ensure complete shipment. Some manufacturers will require you to take inventory and report any missing pieces by a given deadline. This will also allow you to measure and identify all the pieces so you know what to look for when it comes time for construction.

 

Unloaded pieces on ground

Unloaded pieces on ground

 

Squaring the Corners and Measuring Posts

Once the pad has been made, you will need to set the corners and establish a perimeter. For this step you will need:

  • Measuring tape (at least 100 feet, and on a reel)
  • Rebar or stakes (enough for each corner)
  • Masons twine
  • Sledge hammer
  • Flags (enough for each side post)

For this process you will use the 3-4-5 ratio or the Pythagorean Theorem for right angle triangles to establish a 90° angle at each corner. Be sure to measure, and re-measure, and measure again. The structure of your tunnel quite literally rests on whether your corners are square.

 

Squaring corners of high tunnel

Squaring corners of high tunnel

 

For a 30’ wide tunnel, we measured 40’ down one side, and 50’ along the diagonal to establish a 90° angle at each corner.

 

When the corners are established, measure along the sides and mark with a flag where each side post will be set. Double-check your distances by measuring the width between the posts on either side.

side posts

Side posts

Setting the Posts

Once the placement of your side posts are established, you will need to set the posts in the ground. It is possible to install the side posts yourself with an auger or hydraulic post driver, but this is something that will need to be contracted out if you cannot do it yourself. Though there is an added cost for contracting out the work (about $200-$400), hiring a professional will save you time, and will allow the posts to be driven in much deeper.

Hydraulic post driver

Hydraulic post driver

 

A hydraulic post driver used to set the posts for the Lomax high tunnel.

Posts set in ground

Posts set in ground

 

 

 

 

Now you’re ready to start building!

 

 

 

 

 

 

 

 

For more information on the High Tunnel Systems Initiative please visit the NRCS website, or contact your local NRCS area office.

 

Visit CFSA’s page on high tunnel consulting for more information on this service (free for members!).

 

Want to learn more about high tunnels?

Check out these workshops at CFSA’s Sustainable Ag Conference in Durham, November 3-5, 2017:

  • Friday Pre-conference (tickets required)
    • High Tunnel Tour
    • High Tunnel Crop Production: Sequential Planting, Soil Health, and Crop Projections (Friday Preconference)
  • Conference workshops:
    • High Tunnel Basics: Design, Performance, and Management
    • Grafted Heirloom Tomatoes in High Tunnels
    • Year Round Hoop-House Production
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