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ClearSpan Pro “High Tunnel 1” Construction Summary: April 2014 – November 2014

April 8th, 2015 | Posted by JacobThies in Greenhouse - (Comments Off on ClearSpan Pro “High Tunnel 1” Construction Summary: April 2014 – November 2014)

ClearSpan Pro “High Tunnel 1” Construction Summary: April 2014 – November 2014
By JT

Type: 30’ x 100’ ClearSpan Pro Solar Star High Tunnel www.clearspan.com
Full Photo series: www.flickr.com/northslopefarm/hightunnel1

In the 2014 season, NSF purchased two 30’x100’ high tunnels to expand production and season longevity. In this summary, I’m going to lay out our construction methods, talk in layman’s terms about the construction phases, and look into the true cost of the high tunnel including the equipment rentals, labor, and materials.

Looking back at the notes, it was evident that the construction was broken down into six phases. Throughout this summary, I’ll delve into each specific phase in more detail to both provide a record NSF can share with others and for my own learning reinforcement as I oversee the construction of HT1’s twin, HT2.

Phase 1: Map out HT1, confirm dimensions, excavate ground post holes, set ground post holes
The first phase of the HT1 involved what any build calls for: site and design. Siting HT1 was done by MR using his understanding of NSF land contours, solar access, and accessibility to irrigation. After the general location was decided upon, the crew set out to confirm the dimensions of the greenhouse using the 3:4:5 triangle method. This method is as such: any triangle whose sides are in the ratio of 3:4:5 is a right triangle. To properly use this method of measurement, we measured from our first corner post along one edge 3 feet. We marked that measurement. Again from the corner post, we measured along the adjacent edge 4 feet. Finally we measured diagonally across. If the measurement was 5 ft then the triangle is a 3:4:5 right triangle and the corner is ultimately square. We repeated this step for all four corners. Next, we strung the batter boards 3 feet from the construction to maintain permanent line attachments where we could continually confirm, square, and level our measurements. It was critical to have accurate measurements early on as the rest of construction was supported by these measurements.

Here at North Slope Farm, we deal with a subsurface sheet of shale that is impenetrable by hand. In order to excavate the 34 total ground post holes, we first rented a hand hydrologic auger as seen in the picture below.

First attempt at digging post holes

First attempt at digging post holes

The auger pictured above simply lacked the power to dig out the holes efficiently, so we eventually rented a skid steer with an hydrologic auger attachment and aimed to dig the holes to 3’. Most holes were dug to three feet, but a few holes hit bedrock before the three foot mark. We lived with the results and moved on. After the holes were dug, we filled the base of the holes with concrete and set the ground posts. To make sure each post was plumb, level, and the correct height, we confirmed each of those variables with two East to West string lines and used a level to assure posts were plumb. Once all variables were in check, we added a bit more concrete then back filled the holes with soil.

Rented Skid Steer and auger

TH and MR with the rented Skid Steer and auger

Phase 2: Rafter, Rafter Struts, and Purlin Assembly
After setting the 34 posts, the next step is to mount the rafters to the posts. Before we could mount the rafters, we had to first construct them on the ground. All rafter assemblies consisted of four rafter sections joined by a single chevron at the peak.

Rafters assembled & aligned with corresponding posts

Rafters assembled & aligned with corresponding posts

Once we put together the rafters on the ground, we then moved on to attach them to the posts with the help of the John Deere bucket.

Mounting rafter

Mounting a rafter. Note MR adjusting tension of the chevron at ridge.

After lifting a rafter up to the corresponding posts, we aligned the mounting holes and attached the rafter to the post with a bolt into each mounting hole. This is being demonstrated by AM and RM in the photo below.

AM and RM placing bolt to fasten rafter to post.

After the second rafter was in place, we attached the ridge purlin and set the first ridge purlin in place by aligning the pre-drilled holes with the studs of the rafter chevron, and securing the purlin to the rafter using ¼” nuts and washer. The ridge purlins continued to be added as we added more rafters. (During this construction, we waited until all rafters and all ridge purlins were in place before we started to add the support purlins. Looking through the instructions after the fact, we saw that it is best to install all the purlins as the rafters are being installed. For constructing HT2, this point of reference will probably help troubleshoot the stubbornness we experience when attempting to attach the support purlins.)

Raising the rafters & attaching ridge purlin

Raising rafters, attaching ridge purlin, and loosely attaching rafter struts.

To attach the rafter struts, we took a strut and loosely attached it to the ground post flange using the 5/16” fasteners provided. Once loosely attached, we pulled the rafter strut up into position to be aligned with the rafter hole and corresponding hole on the strut. We inserted the bolt through the rafter hole and through the mounting hole on the strut, added a locknut and tightened to secure the strut to the rafter. We would do the same on the opposite side of the high tunnel. It is important to attach the struts before you begin to attach all the purlins. They don’t have to be fully tightened, but having them attached is crucial. In the photo below, AM demonstrating how to loosely attach a rafter strut to the post flange.

AM placing attaching rafter strut to post flange

AM placing attaching rafter strut to post flange

With the first three rafters assembled, we began to mount the first under purlin and secured it to the rafters using the ¼” x 1” bots and nuts. At some points, a purlin and a rafter are used to attach cable assemblies. To do that, we installed the rafter cable plate between the rafter and under purlin.

Phase 3: Cable Installation and Diagonal Struts
The first step to attaching the cable is to attach the eyebolts to the frame. Next we measured the distance between points A and B and cut one length of cable from the roll to the determined length. It is imperative to account for the turnbuckle and the extra cable needed to install the clamps. After doing that, we created the turnbuckle assembly. To create the turnbuckle assembly, we used the diagram on pg 22 of the instruction manual(see photo below).

Pg22 High Tunnel Construction Document

Pg22 High Tunnel Construction Document

The assembly uses a combination of thimbled ends, cable clamps, turnbuckle and turnbuckle jaws to create a tensioning cable that ties each rafter to one another to create a seemingly hurricane-proof design. Below, you can see we used the back of a trailer attached to an ATV as our turnbuckle assembly workbench. This works great as the work bench is mobile and moves along with the crew as needed.

Building the Turnbuckle assembly on mobile workbench.

To attach the turnbuckle assembly, open the turnbuckle to its extended position and check to see how it fits from point to point on the frame. From the diagrams on page 22 (here’s a link to the PDF of the instructions) of the instruction booklet, we attached the first cable to the frame in the location the cable was measured and created for. In the first photo below, JT and TH demonstrate how we used the scissor lift to attach cables to the frame.

Using lift to aid cable installation

Using scissor lift to aid cable installation

We repeated this step on all the cables. Finally, when all the cables were attached, we tightened the turnbuckles. It’s important to not over tighten the turnbuckles as you can pull the posts out of plumb. In the photo below, AM is demonstrating how we used a long screwdriver to turn the turnbuckle to tighten it down.

AM tightening turnbuckles with long screwdriver for leverage to turn the buckle.

To attach the diagonal struts for additional support, we used a vise grip to bend each flattened end of the strut to have the ends of the struts flat against the frame when installed. We positioned the diagonal strut in between the end rafter and the interior rafter with the strut bent end nearer to the rafter on the end rafter and the other end near the bottom of the post on the interior rafter post. Think “diagonal” strut if that sounds confusing! We mounted the struts by drilling holes then inserting bolts with washers through the mounting holes.

 

Phase 4: Frame Check, Poly Latch U-Channel on End Ridge, Attach Ribbon Board & Double Poly Latch U-Channel to Sides
Before moving forward from here, we made sure all frame members were properly secured, that all bolts and screws were tight, and to cover up any sharp edges or fasteners, we cut 12” pieces of repair tape and taped the tops of all interior rafters to protect the plastic. We also cut 4” strips of tape and taped over each rafter splice. To install the Poly Latch U-Channel on the end ridge, from the peak, we attached u-channel to top of rafter every 12”. We made sure to cut the last section flush to the bottom end of the rafter.

Utilizing the scissor lift

Utilizing the scissor lift to attach channel lock to rafters

To attach the ribbon board to the base of the rafters, we used 5/16”x5” carriage bolts. We had to countersink the bolts because the ribbon board we used was thick (a bit wider than 2”). We installed all the carriage bolts then tightened them at the end. We used self-tapping screws and carriage bolts to attach the double poly latch u-channel.

Ribbon board.

RM's flexing muscles and the mounted, double H-channel on ribbon board

Phase 5: Cover Frame with Plastic and Secure
We woke early in the middle of the season with all hands on deck to get the plastic over the frame. We started out by tying ropes to one end of the plastic and throwing the ropes over the HT until we stood on the other side with the rope over the ridge of the HT and attached to the plastic on the ground. All we had to do was pull together, right? Wrong. Heave, ho! We gave it our all, but it proved too heavy and difficult! We stood confounded, MR running up and down the HT trying to push the plastic up into the air with a broom or piece of wood. In the end, we started to flap the plastic up and down – creating the “billowing” effect – which allowed the air to get under the plastic and there it came over the ridge and down to the other side. Success!

Pulling plastic over frame

Pulling plastic over frame

Crew securing plastic on humid morning

Crew securing plastic on humid morning

We secured the plastic on the ridge first. We used the JD bucket to access the peak of the HT. From the peak of West end, we wiggle wired to lock the plastic into the channel.

Wiggle wire through H-Channel

Wiggle wire through H-Channel

Next we secured the opposite end. One person wiggled while the other tried to hold the plastic taut to create tension.

Securing Plastic

Securing Plastic

Thirdly, we locked in one long side with wiggle wire to create tension for the opposite long side. On the opposite side, JT, TH, AM, and RM worked together: two persons held the plastic taut while one applied the wiggle wire and the other one drove our mobile scaffold (the ATV and trailer). We then cut the excess plastic.

All hands on deck.

All hands on deck.

Casey & Colleen enjoying morning of securing plastic to HT1

Phase 6: Baseboards & Roll-up Sides
To attach the baseboards, we established the layout, trimmed the boards to length, drilled holes, and then used u-bolts to attach the boards to the posts. To date, we have yet to set up the roll-up sides.

CH with a big smile! Setting baseboards is fun!

Crew measuring out length for next baseboard

Crew measuring out length for next baseboard

Phase 7: Endwalls
To build the endwalls, we started by measuring out the holes for upright posts. Once measured out, we dug the holes, added concrete then set the posts to plumb and level. We backfilled the holes with more concrete and soil we dug up from the holes. Then we set the horizontal cross bracing. After the cross bracing, we started to attach the polycarbonate paneling.

Master carpenter, and friend of the farm, Ric Stang oversaw JT, RM, and TH as we cut and pieced the paneling together. We had to open the H-channel with the hammer on some of the pieces as the paneling had to enter the h-channel from both the top and the side. We also tried a soap mixture to create some lubrication. Paneling was set by self tapping screws and washers. We had to cut the excess paneling around the end walls to fit it flush to the frame. We used a box cutter to lightly score the polycarbonate, then repeated the light scoring until the poly could be bent. After it folded back, we would be able to bend it back and forth until the piece we wanted cut came off. This was very effective.

MR conducting the orchestra.

Setting endwall panels

Setting endwall panels


NSF High Tunnel #1 True Cost:
In hopes of determining the true cost of purchasing and constructing HT #1, we’ve gone back to the receipts and notes to add up the numbers. At first glance, the high tunnel materials (frame & endwalls) were 75% of the total cost. Equipment rentals tallied 8% of the total cost, worker wages was in at 8%, and additional materials cost 8%. Overall, the numbers below tell us that the true cost, albeit high, is justified with the majority of the capital spent on physical infrastructure, equipment necessary to complete tasks (efficiently and safely) and worker hours. To see it through as a profitable investment, we will have to continue to record data regarding the harvests recorded in HT1.

Equipment Rentals
          Skidsteer & Auger (fuscorentalworld.com) 971.00
          Scissor Lift (fuscorentalworld.com) 565.65
Supplies
          Endwall concrete (wamsnj.com) 138.39
          Concrete for Post Holes (wamsnj.com) 240.00
          70 U-Bolts (http://www.finkles.com) 354.96
          Ribbon Boards (Sweet Sourland Farm) 466.50
          Baseboards (Sweet Sourland Farm) 345.00
          Finkles misc. (finkles.com) 84.59
          Drill bits (finkles.com) 102.56
Endwalls (Growersupply.com) 6,944.81
30’x100’ High Tunnel 8,220.00
Worker wages (approximate) 1,700.00
                                                                       Total:     $20,123

Micro Greens

February 25th, 2013 | Posted by Kyle in Micro Greens | Special Projects - (Comments Off on Micro Greens)

Special Project: Micro Greens

Prepared By KG 2/25/2013

Proposal: Explore the viability of producing micro greens on a small scale. The minimal input of worker hours and materials combined with the resulting high value product will hopefully find this technique financially sustainable.

Execution: I plan to order 4 varieties of micro greens to trial in small quantities and establish a weekly seeding and harvest cycle. Ideally harvest will take place on Fridays and/or Saturdays after work for the weekend markets. The seeding date will be approx. 10 days before harvest, possibly changing with experimentation. I will seed into soil filled trays (old trays in seed shed) and experiment with different modes of covering (soil, vermiculite) and determine which yields best results. I plan to start with 2 trays of each mix and one tray each of the herbs, 6 total trays, and adjust the scale of output based on yield and market feedback. I expect 1 tray to yield about 4-6 half pint clam shell containers. I will keep records of production costs and sales to assess the viability of the project and whether it could be expanded to include more varieties/output.

Materials:

–         Trays (already existing on farm)

–         Potting soil – can be tracked and cost determined

–         Space in Heated Greenhouse, preferable on heating mats

–         Containers for packaging – pint or ½ pint clam shells or some alternative

–         Seed – initial order would probably be around 50-60 dollars

–         Worker hours – Tracked

Varieties:

JSS 2566 Mild Micro Mix

JSS 2567 Spicy Micro Mix

JSS 944 Ital. Large Leaf Basil

JSS 919 Santo Cilantro

Summary: Having completed a season growing micro-greens, my overall conclusion is that it was financially viable on a small scale. The project ran for 20 weeks in total, with an average labor input of an hour a week. During the course of the project I developed and refined the system of production until I finally got it to a place I thought acceptable. The main issue I was dealing with was poor germination and low yield, both of which I feel I eventually got a handle on. See the Notes section for more details.

Below is an overview of the finances of the project. I’ll use the term “unit” to mean 1oz. of micro-greens packed in a clear plastic clamshell.

Expenses:

Total seed cost:            $149.85

Packaging:                    $42.71

Labor*:                        $250.00           *25hrs @ $10/hr (conservative estimate)

Total Expense:  $442.56

Income:

Market Sales:               $1024.00

Net:                             $581.44

Initially production was inefficient due to issues of poor germination and irregular yield. Since generally we sold out and were often only supplying one market, it is reasonable to expect increased sales without necessarily increasing production but by applying lessons learned this past year to increase yield. Even despite these issues starting out, the enterprise proved to be financially viable.

Notes on Technique:

Seeding and Germination– My basic technique for seeding was to broadcast seed into soil filled trays and cover with a thin layer of soil. I used the same potting mix that NSF uses for its seedlings as my growing medium. Seeding was done regularly on a weekly basis to ensure a constant supply. I struggled for a long time with irregular germination, every week varying the process slightly and taking notes on results. Eventually I started using a technique I found here where you stack the trays after watering to create a humidity trap. This technique worked great! I didn’t have any trouble with germination after switching to this method; I only wish I discovered it sooner. One thing to watch out for is to un-stack the trays at the right time, I was a day late once and lost a few trays worth of micro greens which had grown into the bottoms of the next tray in the stack.

Growing– Daily watering a must. The two week interval between seeding and harvest worked in mid-summer, but as days got shorter I ran into problems with growth. Switching to three week intervals solved the problem and would probably use a three week interval from the start in future.

Harvest– I harvested after first set of true leaves developed. Harvested using sanitized scissors into a clean rubber bin and packed the night before market, then refrigerated.


Notes on Materials:

Packaging– Used 8.oz plastic deli container. Good size, when full held approximately 1.oz of micro greens. Nice snap seal, clear to display product, flat top for label. Cost around $0.15 per unit.

Trays– Used old 11x21x2.5 inches greenhouse trays. Worked great, easy to handle and clean, plus they didn’t cost anything.

Greenhouse Space– Space wasn’t an issue as the project was started on 6/23, after a lot of space was freed up in the greenhouse. If done again next season, could maintain this size operation on a single table, although having a sunny spot is vital.

Seed– Initial ideas of having a large variety of micro green types didn’t seem practical when faced with reality. The key to having this be profitable on a small scale is keeping worker hours low, and uniformity in the process helps achieve that goal. A large selection of varieties, each with different needs and days to maturity, adds complexity. I settled on two mixes, one mild and one spicy, with similar requirements.

Improvements:

Using what I’ve learned this past year will mean an improvement in production. To make the most of this increase some marketing work can be done. Giving out free samples early on at market could help increase sales and introduce customers to the product which they may not be familiar with. In addition, I found bringing un-harvested trays to market for display was aesthetically pleasing for the stall as a whole, attracted attention to the product, and introduced the costumer to more of the process of growing the product.

Hoop House Tomatoes

October 6th, 2011 | Posted by steven in Hoop House Tomatoes - (Comments Off on Hoop House Tomatoes)

Special Projects – Hoop House Tomatoes
Trellis
Prepared by ST 10/6/11

Grafted Heirloom tomatoes were trellised with the double leader technique. Each tomato plant’s leaders were pruned except for two which were clipped to its own individual string hanging from the top of the hoop house. This provided adequate airflow for the plants and made it easy to harvest in an efficient manner. We mulched the beds and aisles with hay for weed suppression and to prevent soil from contacting the plants. The outside rows were non grafted indeterminate red slicing tomatoes. We trellised and pruned them using the same method for the grafted tomatoes. Soil moisture sensors were placed in two of the rows to inform us when and how much to water. On average we watered once a week for about an hour. This changed according to the weather. On hot weeks we watered twice a week and during rainy periods we did not water at all. A humidity chamber was built for the newly grafted tomatoes. This consisted of a tent of plastic under the greenhouse table. Cardboard was placed on top of the table to block light out. This created the right environment for the grafts to heal. I learned this method from the first farm I worked at: Blooming Glen Farm.

How to Graft: Grow seedlings of heirloom and rootstock so their stems are about the thickness of a pencil. Cut the top of the root stock off. Cut a downward slit on the rootstock with a matching upward slit on the plant you want to graft. Insert the cuts together and plant into a single pot. Hold plants together with graft clips and mist the cut with a spray bottle. Place under the humidity chamber for 3 to 5 days. Pull the plants out and cut halfway through the base of the heirloom. Twist tie the plants to a skewer for support. Water the base of the plant gently to avoid soil splash. Place the plants back into the humidity chamber for another 3 to 5 days. Take the plants back out and cut all the way through. Now the root stock will be attached to the heirloom. There are some variables to this procedure. Observation of the plant’s health is vital. Slowly introduce the plant back to full sunlight before planting.

Root Stock: Maxifort

Heirloom Tomatoes: Brandywine, Striped German, Paul Robeson, and Black Prince

Non grafted Tomatoes: New Girl

4 beds planted: 2 Outside beds new girl, 2 inner beds with grafted heirlooms (1/2 of bed for each variety)

Single row planting at 18” spacing

Important Dates:

3/4 seedlings were planted

4/22 to 4/27 tomatoes grafted

5/13 tomatoes planted

7/12 first harvest

9/23 last substantial harvest

Yield from 300 row feet of tomatoes:

Grafted Heirloom-1410#

Red-1139#

Worker Hours:

Seeding – 1 hr

Grafting – 16 hrs

Planting – 1.5 hrs

Trellising – 30 hrs

Harvesting – 32 hrs

Clean up – 12 hours

Winter Production – Introduction

October 19th, 2010 | Posted by steven in Special Projects | Winter Production - (Comments Off on Winter Production – Introduction)

Winter Production
Introduction, prepared by ST

October 19, 2010

Intent: To extend the growing season of leafy greens, lettuce, and root crops to serve our existing outlets such as Hopewell Farmers Market, Nomad Pizza, and Zone 7.

Parameters:

• Capital Investment; North Slope Farm

• Daily management; RCM and ST

• Site Details; infrastructure and fields managed by North Slope Farm
        o 6 outdoor low tunnels 5’ W X 40’ L
        o 2 unheated green houses
                  Farmhouse Gothic; 28’ X 84’ w/ 4 beds @ 48” wide
                  Ralph’s House; 27’ X 76’ w/ 4 beds @ 48” wide
        o 1 heated Greenhouse for table top production

• Outdoor low tunnels will cover crops such as tatsoi, spinach, and arugula. Two cuttings are expected for harvest. The hoops are constructed of 3/8” X 12’ rebar covered in recycled drip tube. The outer skin is 6 mil plastic that is 13’ W X 50’ W. A layer of remay may be added to the interior for extra warmth and reduced temperature fluctuation.

• One hoop house will be used for direct seeded crops such as spinach, arugula, tatsoi, and salad mix. The other hoop house will be used for transplanted crops such as kale, scallions, leeks, swiss chard, fennel, and beets. Carrots and radishes have been direct seeded into one open bed early, as the other beds are currently occupied by late planted tomatoes.

• .The heated greenhouse will be used for table top production of salad mix. Potted herbs such as parsley and basil will also be grown.

• Regular records will be kept of costs and production. Worker hours and market income will be tracked. The materials purchased should be able to be reused, improving profit margins in future seasons.
          o $385.60 for seed costs
          o $370 for plastic and remey over three years
          o $90.80 for rebar and sand over ten years
          o $108 for plastic sandbags over three year
                      Total $954.40 for one year

• Workers will have to be mindful of temperature to open and close the low tunnels or remove remey in the hoop houses. The difficulty of winter weather will be a challenge in harvesting, handling, and marketing. Costs will be calculated against profit to see if this is a viable operation for North Slope Farm.

• The inspiration for winter production at North Slope Farm came from a lecture at the NOFA summer conference. A Connecticut grower, in zone 3, presented a low tech option of covering field crops to produce a nutritious and profitable product for his customers during the winter time. This inspired me to keep producing local organic food through the winter. I hope that having a consistent presence through the winter will support existing customers and win over new customers. Winter production also keeps workers on the farm and in constant dialogue with agriculture. Some challenges we have already faced have been 30mph winds blowing off our outdoor low tunnels. Did we cut the plastic too short? Are the sandbags not filled enough? Do the tunnels need to be smaller? At what temperature should we open and close the tunnels? These are questions that have already risen and in the middle of the winter I am sure there will be many more. To supply fresh local organic food is the main goal and we will need support from our community to make it a reality.

Winter