Portable Anti-Viral Septic System

Washrooms are a crucial component of any building and PASS offers a virus-free alternative to the conventional restroom trailer for rent in events and construction sites. Currently, portable restrooms are not known to be particularly sanitary and allow for easy transmission of viruses and bacteria. The units are designed to be transportable and will be constructed in both a 20ft and a 40ft shipping container option as needed by the client. Heaters and spray foam insulation allow for the PASS unit to maintain 5ºC inside in even -41ºC weather. The 20ft PASS unit includes one standard and barrier free washroom. The 40ft shipping container has six standard washrooms.

STANDARD WASHROOM

The standard washroom includes sink, soap pump, toilet, urinal, paper towel dispenser, toilet paper dispenser, and garbage disposal.

BARRIER FREE WASHROOM

The additional barrier free features include wheelchair accessible sink, ramp and platform to access washroom, accessible door opening system, handrails along the wall beside the toilet, and 1.5 m diameter open space to permit wheelchair to turn.

DISINFECTION CYCLE

Our design for a portable washroom aims to reduce potential transmission of bacterial pathogens by providing a sanitary solution using a germicidal ultraviolet lamp installed in each washroom.  Ultraviolet Germicidal Irradiation is a proven method used to disinfect water, air, and surfaces. It is most common to use a UV lamp at a 254 nm wavelength, also known as UVC, to inactivate a wide spectrum of microorganisms, such as viruses and bacteria.

There are many risks associated with using UVC lamps to terminate cells. UVC is intensely absorbed by most organic materials meaning there are additional considerations for this project such as potential exposure to humans and choice of materials used in the washroom designs. Each washroom features a door locking mechanisms that works in tandem with sensors to ensure the restroom is vacant and the door is closed before starting the disinfection cycle. A red indicator light turns on for the duration of the cycle to alert users that the washroom is unavailable and when it is occupied.

Currently, most portable washrooms are made of plastics which are vulnerable to compound breakdown when exposed to UV light without proper protection. Plastics in general are susceptible to colour fading, loss of strength, cracking, and even disintegration due to UV exposure. All material chosen to be within the exposed area of our shipping container has superior UV resistance such as metals, ceramics, and porcelain.

TOUCHLESS CONSIDERATIONS

In areas that are high touch surfaces and cannot be changed out with a foot pump (such as the door locking buttons) a nanoSeptic sticker is used that kills bacteria and viruses that come into contact with it.

Standard Washroom Design Features:

Barrier Free Washroom Design Features:

• Soap pump and toilet operating automatic sensors
• Automatic sink sensor

Our design can be built from prefabricated materials. It follows specific Canadian codes and standards to ensure our design is compliant with national engineering practices listed below.

• National Fire Code of Canada
• National Plumbing Code of Canada
• National Energy Code of Canada for Building
• National Building Code – Alberta Edition
• International Plumbing Code – Methods of Venting Plumbing Fixtures and Traps
• ANSI/ASHRAE Standard 62.1-2013 – Ventilation for Acceptable Indoor Air Quality

To determine if the PASS unit can be used in a real life application, multiple calculators have been created to determine how many 20ft or 40ft units are required for an event or a construction site. These calculators factor in the time it takes to run the disinfecting germicidal UV light cycle.

These calculators consider if:

• alcohol is served at the event
• the percentage of women and men who will be using the PASS unit
• the time the unit(s) are used (duration of event or workday)
• if a barrier free washroom is required

PASS EVENT APPLICATION EXAMPLE

Global Fest is a yearly firework festival that happens in Calgary over five nights. The below table is assuming that 50% of women are in attendance to Global Fest that runs 6 hours, and that alcohol is served with a maximum attendance of 2000 people.  There must be one barrier free washroom to ten standard washrooms. This table is double what is generally recommended to factor in the disinfection cycle.

Number of Event Attendees	Number of Individual Washrooms	Number of 40ft PASS Units	Number of 20ft PASS Units	Ratio of Standard to Barrier Free Washrooms
250	8	2	2	14:2
500	10	2	2	14:2
1000	16	3	2	20:2
2000	30	5	4	34:4
3000	42	7	6	48:6
4000	58	10	6	66:6
5000	72	12	7	79:7
6000	84	14	8	92:8
7000	96	16	9	105:9
8000	112	19	13	127:13

For the Global Fest event it would be appropriate to have five 40ft PASS units and four 20ft PASS units. The tanks for all units will need to be filled and emptied once a night over the course on the five-night event. This could mean that the next day a maintenance team can be sent to prepare the PASS units for the next night.  Assuming that there can be two event contracts that can be secured in one year for roughly $60,000 each (like Global Fest) the PASS units will see a return on the initial investment in two years.

3D MODELLING

The design team chose prefabricated materials that would be used to build a physical PASS unit and modelled each component in SolidWorks. This was to ensure that each component would fit inside the washrooms and that the user would have enough space to use the facilities. The piping and framing were built in SolidWorks to ensure it would fit within the space constraints of the shipping container unit while still meeting national building and plumbing standards. The modelling is an excellent visual for our design and would act as a blueprint if a physical unit was ever constructed.

DISINFECTION CYCLE TIME

Without access to lighting simulation software, the design team had to come up with a solution to determine an estimation of a germicidal UV lamp exposure time and dosage that would meet a goal of 99.9% deactivation of viruses and bacteria. In the model the distance from each surface to the light is measured to determine the light intensity on that surface, an example of this is shown below.

The sink was an area the team wanted to focus on since that is where most common touch surfaces are. By averaging the calculated recommended exposure time from multiple locations on each surface, the team determined the overall recommended exposure time for the 20 ft unit standard washrooms is 5 minutes, the barrier free washrooms is 6 minutes, and the 40 ft unit standard washrooms is 4 minutes.

The design team’s goal was to ensure the PASS unit would be affordable to build and could be used as a replacement to many restrooms trailers on the market. Below the table shows the initial capital investment required to build each PASS unit. There is a 15% contingency applied to each total to factor in any changes that might need to be made with material procurement or during construction. Both PASS units are competitive with the initial building costs of restroom trailers currently on the market.

	40 FT	20 FT
Total Cost of Components	$31,154.40	$18,823.85
Construction Material/Labour	$16,239.90	$11,113.57
Contingency (15%)	$7,109.15	$4,490.61
Grand Total	$54,503.45	$34,428.04
Competitor Cost	$70,000-83,000	$57,500-70,000

PASS CONSTRUCTION APPLICATION EXAMPLE

To show how feasible the PASS units are to build and use a real life example of a construction site with 60 workers is examined. The below table is based on how many portable washrooms are chosen for a 40-hour work week or 12-hour workday.   

Number of Workers	Number of Standard Washrooms	Number of 40ft PASS Units
01-10	2	1
11-20	4	1
21-30	6	1
31-40	8	2
41-50	10	2
51-60	12	2
61-70	14	3
71-80	16	3
81-90	18	3
Over 91	Additional 2 washrooms per every 10 workers	3+

In general, it would be wise to assume that two 40 ft units can be used in this construction project assuming the client does not require a barrier free washroom. A vac truck and maintenance crew is needed twice a week to fill the fresh tank and empty the septic. The PASS units in this example need to be filled/emptied every 3 days. A return-on-investment calculation was determined for the construction site example and the PASS unit will be profitable in 2 years.