water efficient vehicle wash design

7/30/2019 Water Efficient Vehicle Wash Design

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INDIAN PLUMBING TODAY GREEN PLUMBING

Most of us see hundreds of cars,trucks, buses, police cars,

ambulances, fire trucks, and subwaycars in a typical day. These vehiclestypically are washed on a regularbasis, using thousands of gallonsof municipal water. This articlediscusses some of the environmentalimpacts of vehicle washing, theways vehicles are washed, and waysto improve the efficiency of thesesystems.

Environmental Impacts

We first must review how water moves

and is purified naturally. In theearths biosphere, water evaporatesinto clouds using energy from the sunand then falls as rain back to theearth, where it enters the surface andgroundwater system. All along theway, water is treated.

When you wash your car in yourdriveway, you change this naturalprocess. You probably use municipalwater, which does not begin at theend of the hose. It most likely comesfrom a municipal system in which

the water was pumped from anatural source, treated to drinkingwater standards, pumped to yourhouse, and then sprayed onto yourdirty car. You know its high-qualitywater because on a hot summer day,you might take a drink from thehose without risk of getting sick.

The water flowing off your car isanother story. During the carwashit has collected a cocktail ofmaterials that can be hazardous toliving things. The wastewater

Water-Efficient VehicleWash Facility Design

Winston Huff

contains organic materials mixedwith chemicals from your car such

as oil, antifreeze, and asbestos fromthe brake dust. Most of the time,this water flows into the stormsewer system and goes untreatedinto a natural water source. In somelocalities, concerns about naturalwater sources may revolve aroundindustrial pollution and untreatedwastewater plant discharge fromcombined sewer and storm systems.However, in most areas the largestproblem for natural water streamsand rivers is runoff from hardservices such as parking lots, roofs,

roads, and driveways. This runoffcontains many toxins from vehiclesand flows untreated into naturalwater sources.

What can we do about this problem?One step in the correct direction isto maintain our vehicles so theydo not leak automotive fluids.Another step is to collect and treatrunoff from areas where vehiclesare parked and stored. The laststep, discussed in this article, isto reduce the amount of municipal

water used in washing vehicles andreducing the runoff from thiswashing process.

Vehicle Wash Methods

Because washing your car inthe driveway sends untreatedcontaminants into the ground orstorm system, this is thankfully notthe usual process for cleaningvehicles. One common method isthe wash bay method where wateris sprayed onto the vehicle with a

spray wand. The first step in thecleaning process is the pre-rinse

or pre-soak, in which water issprayed onto the vehicle, collectsthe solids and contaminants, andwashes these materials down thedrain.


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The next cycle is usually the washcycle, which uses detergents andcleaners while brushing the vehicle.In this cycle, the operator has somecontrol over what products to useand what products work best withthe water reclaim system. In the

typical wash bay, this is done byhand and not automated. This waterthen washes down the drain.

While many other processes may beused during a vehicle wash, typicallythe next step is the final rinse. Inmost cases, the quality of the wateris important because contaminantsor hardness can leave residue on thecar. In the bay-type wash, thisusually is done by hand and is notautomatic. This water then washesdown the drain.

The last step is the drying phase.This can be done with an air dryeror a towel. The dryer system can uselarge amounts of energy, while the

towel method uses energy to washand dry the towels.

The bay-type system can be self-service or a commercially runoperation. In addition to the bay-type system is the automated

conveyor system that is used bylarger commercial washingfacilities. The stepsremain roughlythe same, but the methods to dothese steps are vastly different fromthe bay-type system.

Efficient Design and Operations

What about the water issuesin each of these steps? Therecommendations in this articleare for new construction projects.Operators of existing facilities

should be aware of these issuesand consider modifying theiroperations methods, equipment, orprocedures to reduce the amountof water used.

In new construction projects, watermeters should be installed at thewater entrance to the building andwater feeding each major system.The meters should be the type thatcan communicate to a buildingmanagement system or a vehicle

wash management system. This willhelp the building operations teammonitor water usage to improve onbuilding operation efficiencies.

An efficient operation first shouldconsider not using municipaldrinking-water quality water duringthe pre-soak because this highquality water is not required in thiscycle. Instead, the pre-soak can userecycled water. Reclaimed watershould be used in gun-type,undercarriage nozzles, presoak

cycles, mat cleaning, and floorcleaning.

The wastewater from the pre-soakis typically the dirtiest water in the


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washing cycle. This water will contain the hazardous cocktail of solutionsthat can harm plants, animals, and people if not properly handled.Contaminants can include substances such as engine oil, asbestos, andantifreeze. Separators should be installed on the waste line from the facilityalong with a way to monitor the water as it leaves the separators. Inmost cases, this wastewater goes to the municipal waste system and notthe storm water system. This waste should not go to the natural stormwater system because of the damage these materials can do to the naturalecosystems receiving this water.

During the wash phase, conveyor or tunnel-type systems can use a touchless procedure that uses large amounts of water at high pressures to actas a brush to clean the vehicle. Thus, to reduce the amount of water intunnel-type systems, friction brush systems should be used instead oftouch less systems. The manufacturer or the operator of a hand-brushsystem needs to know the importance of cleaning brushes and using correctmethods to minimize the damage that can be done to a vehicle with thebrush system.

In contrast to the pre-soak phase, the final rinse phase uses the highestquality water in the facility. Many systems use higher quality water thanmunicipal water, such as water purified by reverse osmosis (RO), to cleanthis water. A typical RO system backwashes from time to time to clean thefilters. This backwash water is not RO-quality water, but it is very high-

quality water and can be collectedand used for other water supplies.When reverse RO or other filteredwater is used for the final rinse, thebackwash water from the fi ltersystem can be collected and used inthe water reuse system.

Some RO equipment operates bybackwashing water down the floordrain based on a timer, not when thefilters need cleaning. Thus, RO andother filtered water systems such aswater softeners should be specifiedwith a pressure differential backwashsystem that only backwashes whenthe filters need cleaning.

The amount of water flowing throughthe system can be reduced. Forexample, low-flow, high-pressure

nozzles can be used on hoses andwater brooms. During the washingprocess, water will splash off thevehicle onto the floor. To reduce theamount of floor washing, floordrains should be located near placeswher e liqui d di sch arges fromequipment. Facilities sometimes usehand-operated wands or sprays towash vehicles or wash down thefloors after vehicle washing iscomplete. If no water control valvesare on these sprays, they can flowwater for long periods when they are

not in use. When these wands areused, install automatic shutoffvalves on hoses and water-usingequipment.

Sound operating practices areimportant for an efficient facility.Nozzles can be bumped andmisdirected; and cleaning solutionsoften are purchased based on upfrontcost, not their effectiveness. Thefacility can reduce water use byusing the proper cleaningequipment, settings, and

orientation. Spray nozzles with a fanshaped spray installed parallel tothe spray bar also can reduce waterusage.

During the drying phase towelsmight be used to dry the vehicles.Equipment with a high CEE ratingshould be used. On-site towelwashing should use high-efficiencywashing machines with a Tier 3 CEErating and a water factor of 4.5gallons per cubic foot of washercapacity.

Before designing a vehicle wash facility, check out these resources:

International Carwash Association: carwash.org Watersmart Guidebook: A Water-use Efficiency Plan Review Guide

for New Businesses: allianceforwaterefficiency.org/WaterSmart_Guidebook_for_Businesses.aspx

MTA NYC Transit New Corona Subway Car Maintenance Shop and

Car Washer: First NYCT LEED-Certified Facility and ISO 14001 EMSConformance Example, Thomas Abdallah, PE, Chief EnvironmentalEngineer, MTA New York City Transit, New York City.

The Final Report of the Blue Ribbon Commission on Sustainability andthe MTA: mta.info/environment/pdf/draft_final3.pdf

New York City Transit and the Environment: lirr.org/nyct/facts/ffenvironment.htm#swmp


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IPT

Winston Huff, CPD, LED AP, is a project manager, plumbing fireprotection designer, and sustainable coordinator with Smith SeckmanReid Consulting Engineers in Nashville, Tenn. He is on the U.S.Green Building Councils Water Efficiency (WE) Technical AdvisoryGroup (TAG). He was the founding editor of Life Support and BiosphereScience and has served as its editor-in-chief. He is president of

Science Interactive, an organization promoting biosphere science.

Reprinted with permission from the April 2010 issue of Plumbing Systems & Design. AmericanSociety of Plumbing Engineers. All rights reserved.

The plumbing engineers can provideinput on other systems to ensureefficient building design andoperation. For example, fuel cellscan be installed on buildings togenerate electrical power. Abyproduct of these systems is a

high-quality hot water that can beused in the washing operation.Geothermal systems may be used topre-heat water for the washingsystems. In facilities that use largeamounts of hot water, solar waterheating systems can be a viableoption to reduce operational costs.

Reclaimed Water

In addition to the water collectedfrom the water filtration system,rainwater can be collected and used

in the wash system. In large urbansubway systems, groundwater isconsidered nuisance water, whichcan be captured and treated for thewash systems. Additionally, rainharvesting may make sense.Rainwater is usually soft whencompared to typical municipalwater and as a result is a goodsource water for the wash andrinse cycles. When this is done, therainwater must be collected andstored using best rainwaterharvesting practices.

In some facilities, collecting thefinal rinse water and using a graywater system to treat, filter, andstore the water makes economicalsense. Usually the gray water is usedfor the pre-soak phase of thewashing cycle. Most large vehiclewa sh ma nufacturer s makeprepackaged vehicle wash systems.In many cases, installing a reclaimsystem while remodeling an existingvehicle wash facility will pay for thesystem in a few years. Plumbing

engineers should use these waterrecycling systems wheneverpossible.

One way to encourage organizationsto use efficient vehicle washfacilities is through a certificationand recognition program. Onestudy from the InternationalCarwash Association (ICA) foundthat recognit ion of water-conserving car washes throughcertification programs can helpwater planning agencies and

utilities gain year -round savings in partnership with professional car washoperators.1

When starting the design for a new construction or major renovationproject; the plumbing engineer, owners project manager, building operator,civil engineer, architect, equipment supplier, and mechanical engineershould meet before the schematic design phase to compare the water

demands of the building to available water sources. On facilities withlarge water demands, such as vehicle washing, the team should developconceptual designs of systems to reduce potable water usage. The plumbingengineer should develop a water balance calculation (demand vs. alternativewater sources) for the facility. It determines available watersourcessuchas rainwater, and waterusessuch as pre-soak. This water balance can beused to design the rainwater harvesting and gray water systems.

Acknowledgement

In addition to thanking all the sources listed in this article, a specialthanks goes to Steven Winter and Associates in their Washington, D.C.,office and the New York City Department of Design and ConstructionSustainable Design Office.

This article is not intended to be a complete design or operations guide.Rather it is intended to enlighten, inform, initiate, and inspire design andoperation teams to new design and operational solutions. Efficient designand operation is not a fad or trend; it just makes sense.

References

1. Chris Brown, Water Use in the Professional Car Wash Industry,International Carwash Association, 2002.

water efficient vehicle wash design

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