Vegetable Wash Station Design 2

Vegetable Wash Station Design 2 - Hoophouse

hoophouse diagram

This upgraded wash station design is enclosed in a commercially available hoophouse structure with a poured cement floor. The hoophouse is divided into two sections, namely a wet section and a dry section, separated by a plastic curtain hung from the rafters of the hoophouse.

The WashStationUpgrade.pdf file contains a materials list, placement and size of components and other details.

The wet section contains this equipment:

  • portable hand washing station - see photo.
  • vegetable wash line - see photo.
  • barrel washer - see photo.
  • two sinks and a drying rack from the first design.
  • two 65-gallon water tanks - see photo.
  • pressure washer station with roller conveyors - see photo.
  • a spin-dry workspace for removing excess water from the washed leafy greens.
  • storage shelving for materials used on the wet side of the hoophouse - see photo.

The dry side has space for these functions:

  • roller conveyors (see photo) and table space that function as packing space for the clean and cooled vegetables
  • storage racks, used for storing packing boxes, plastic bags, empty vegetable totes, and other supplies
  • space for additional pack lines or storage shelves (easily accommodated in a 30 X 72-ft. hoophouse)
  • a walk-in cooler on one-half of the end wall to facilitate easy handling of vegetables in and out of the cooler (rest of the end-wall space can be used when moving vegetables to the delivery truck).

Additional roller conveyors may be desirable for moving either dirty vegetables into and away from the listed wash equipment, as well as moving clean vegetables to the cooler for storage. The use of hand trucks (see photo) for pallet-size loads or handcarts (see photo) for smaller quantities also permits easy movement of products throughout the hoophouse. An effort should be made to keep a separate set of handling equipment for the wet side and the dry side.

The component pieces of equipment are available from vegetable/greenhouse supply companies and industrial material handling supply companies. 

Questions to answer when considering a site:

  • How level is the construction site?
  • Is there vehicle access for unloading vegetables to be washed as well as loading packed vegetables for commercial delivery?
  • Does the site have access to suitable drainage fields for dirty wash water?
  • What is the travel distance between the site and vegetable fields?

About the hand wash sink:  This sink is for wash station operators to wash their hands prior to washing vegetables and is not intended to be for "after bathroom"  use.

  • NEVER USE the hand wash sink for washing vegetables.
  • NEVER USE a vegetable washing sink for washing hands.

The best practice is to always wash your hands with soap prior to washing vegetables.

About equipment and components

  • The vegetable wash line includes a vegetable washer, brush dryer, and rotary packing table, and is used to process various round vegetables, such as potatoes, tomatoes and winter squash.
  • The barrel washer is best suited for washing root crops such as beets, carrots and parsnips (and also  potatoes).
  • Two sinks and a drying rack are included in the layout to allow washing smaller batches of vegetables.
  • Two 65-gallon food-grade water tanks are used to wash larger batches of leafy greens, green beans, brassicas and peas.
  • A spin-dry space has been identified in the layout. This space would contain equipment to spin the excess water off washed leafy greens.
  • The spin-cycle on a washing machine with a stainless steel liner works well for this purpose.
  • A 5-gallon leafy greens spinner works well for smaller batches of greens (the small table in the layout can be used to hold the spinner).

A pressure wash station is shown near the middle of the hoophouse, next to the dividing curtain.

  • A low-pressure electric power washer works very well to spray off dirt from root vegetables, especially if a variable width spray nozzle is used on the spray wand. The size of the pressure washer is not critical, since the smaller electric units provide plenty of pressure. Be sure to choose a model that is reliable and contains an adjustable spray nozzle. A wider, lower pressure spray setting prevents damage to the vegetables being washed. 
  • By hanging the spray wand from the hoophouse frame, arm and shoulder fatigue from holding the wand is reduced. One hand can be used to direct the spray while the other rotates the vegetables.
  • Be sure to use durable, waterproof gloves when working at this station.  Wearing a water repellant apron is also desirable.
  • Vegetable trays from the first wash station design work well to hold the vegetables to be spray washed at this station.
  • Roller conveyors have been added as a convenient way to support the trays for washing.
  • Roller conveyors also have been added to the load-and-unload side of the mechanized vegetable washing equipment, in order to facilitate staging vegetables before and after each piece of equipment.
  • Plastic drop curtains divide the hoophouse in half, separating wet and dry operations. The curtains can be cut from extra greenhouse plastic leftover from construction of the hoophouse.
  • A storage rack on the wet side of the drop curtain provide space for items used in washing the vegetables, including washtubs, aprons and gloves for workers, and other miscellaneous supplies.

About the cement floor

Design and layout of this floor can be a bit tricky because of the need to have a trench down the middle of the wet side of the hoophouse. Both sides of the poured floor along the trench need to slope inward, allowing wash water to easily flow into the trench.

The trench should be about 1 ft. deep, covered by a metal floor grate to allow hand trucks and foot traffic to move easily over it. The trench also needs to be slightly sloped down from the center of the hoophouse toward the end wall, where a 4-6 inch PVC drain line is installed.

This drain line collects used wash water and drains away from the hoophouse. It should be buried underground (to prevent freeze-up during cold months) and run from the hoophouse to a grass field.  Soil washed from vegetables will build up in the trench over time, necessitating a regular cleanout of the trench. Contact a commercial contractor experienced with sloping, poured concrete floors before tackling this part of the construction.


It is assumed that water lines and electric lines required by the various vegetable washing equipment have been run inside the hoophouse. Consult appropriate contractors to install these services. 

Overhead lighting can be installed to facilitate vegetable washing in low-light conditions. Again, appropriate requirements must be met when installing these services – consult with a suitable contractor.

Equipment costs for heating and cooling hoophouse have not been included in this project. There are many commercially available options for heating including oil and propane furnaces, as well as wood-fired heat sources.

The addition of heat to the structure will extend the number of operating days. Cooling can be accomplished through natural ventilation, shade cloths and fans. The selection of a hoophouse with high (5-ft.) sidewalls, fan-powered end-wall peak vents, and large end-wall openings will improve the natural ventilation of the hoophouse. Overhead fans and floor fans will improve ventilation inside the structure. A high-density (80 percent) roof shade cloth also will reduce the solar radiation inside the structure during summer days.

Equipment for this design layout will cost roughly $12,700. The hoophouse will cost around $3,200 and the cement pad will be around $4,000, making the total package roughly $20,000, plus the cost of heating, cooling, lighting, and water options.