United States Department of Agriculture

Forest Service National Technology & Development Program NTDP Tech Tips

ForestService

National Technology & Development Program

1373–2314P–NTDPFacilities

May 2017

Resources to Help Prevent Flooding of Vault Toilets in Recreation Sites on National ForestsKathleen C. Marks, Project Leader

Highlights• Concrete vault toilets found at developed rec-

reation sites on national forests sometimes fill

with rainwater, snowmelt, or high water.

• In areas where flash floods or recurring floods

occur, the best option is to redesign, relocate,

or remove the toilets.

• CXT Concrete Buildings in Spokane, WA,

designed a riser cover to seal the riser hole for

existing concrete vault toilets located in flood

plains.

Concrete vault toilets that flood are not a new problem. Most developed recreation sites on national forests have precast concrete vault toilets (also known as sweet smelling toilets, SSTs).

The concrete vaults sometimes fill with rainwater,

snowmelt, or they are flooded by high water. This

tech tip discusses vault toilet flooding and identi-

fies publications that may answer your questions on

vault toilets, introduces some of the new construc-

tion modifications by vault toilet manufacturers, and

provides some other ideas for vault toilets in difficult

locations. Depending on the severity of flooding,

there are different solutions. National Technology and

Development Program staff reviewed ways of pre-

venting vault contents from escaping if flood waters

inundate the structure.

ReviewThe following publications provide information about

concrete vault toilet placement, maintenance, and

troubleshooting (figure 1).

“In-Depth Design and Maintenance Manual for Vault

Toilets” is the original U.S. Department of Agriculture,

Forest Service, manual on design, location, and main-

tenance for the complete vault toilet system.

“Maintenance Issues and Repair Guidelines for Pre-

cast Concrete Toilets and Utility Buildings” discusses

cracked panels, peeling paint, manufacturing infor-

mation, safety and structural issues, and warranty

and contract issues.Figure 1—These publications provide information about vault toilet placement, maintenance, and troubleshooting.

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“Vault Toilet Interception Analysis” provides solutions

for the most common flooding and infiltration prob-

lems with vault toilets. Common causes of flooding

are locating roof driplines directly over manhole lids,

failing gaskets on manhole lids, and locating vault

toilets in low areas where water infiltrates through

the joint between the vault and the building slab.

Solutions discussed are a manhole lid retrofit; swale,

ditch, French drain, and retaining wall construction;

and grading or paving measures.

“Micro-Flush Toilets” is an introduction to floating

sanitation facilities (FSFs) and land-based movable

sanitation facilities (LSFs). The FSFs can be attached

to existing dock structures or anchored in open

water with a unique, self-leveling anchorage system

that accommodates up to 100 feet of water-level

fluctuation with no labor or maintenance required.

The floating platform is 20 by 20 feet and carries a

1,000-gallon holding tank, which is equivalent to the

capacity of a standard vault toilet. The LSFs are mov-

able, solar-powered, self-contained, micro-flush toi-

lets located along the shore of the reservoirs. As the

water level fluctuates, the toilets are moved to a new

location. The original LSFs were moved with a front-

end loader. Empty, they weigh about 4,000 pounds.

The newer units have removable wheels and can be

towed to another location. The LSFs have a 300-gal-

lon clean-water tank and a 400-gallon waste tank.

For information about FSF and LSF manufacturers

and pricing, please refer to “Micro-Flush Toilets.”

New TechnologyDetermining the cause of a problem is the first step

toward solving it. Vault toilets should be located

out of the flood plain: “high and dry.” Recently

installed precast concrete vault toilets are likely to

be designed and constructed using materials that

reduce or eliminate the problems of existing, older

vault toilets. Newer concrete mixes include additives

that form a better, more watertight barrier to prevent

contents from escaping the vault and excess water

from penetrating the vault.

The vault rim and floor slab also may be interlocked

and sealed with new products that expand and con-

tract with temperature changes and remain flexible

over time to provide a better seal.

For Areas With Extensive FloodingCXT Concrete Buildings in Spokane, WA, developed

a riser cover design to seal the riser hole (figure 2) for

existing toilets improperly placed in the flood plain.

The design also helps when toilet closure beyond

locking the door is necessary. Employees can use the

cover seasonally to prevent any exchange of vault

liquids during high water. The CXT cover would be

appropriate in locations that have some flooding dur-

ing the off season but not at locations susceptible to

flash flooding during the visitor-use season (employ-

ees must remove the riser to install the cover).

Please note that it is against Forest Service policy to

place toilets in the flood plain or flood-prone areas

(FSH 7409.11, as well as other State and Federal

laws). For toilets already in these areas, the best

options are to redesign, relocate, or remove the

toilets.

SummaryPotential solutions for concrete vault toilet flooding

do exist. However, proper site location and appropri-

ate design and installation will reduce future issues

with vault inundation.

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Figure 2—Shop detail drawing of the CXT Concrete Buildings riser cover. —Courtesy of CXT Concrete Buildings.

ReferencesCook, Briar. 1991. In-depth design and maintenance manual for vault toilets. Tech Report 9123–1601–SDTDC. San Dimas, CA: U.S. Department of Agriculture, Forest Service, San Dimas Technology and Develop-ment Center. 59 p. Available at and to Forest Service and BLM employees on the internal Forest Service network at .

Kees, Gary. 2004. Maintenance issues and repair guidelines for precast concrete toilets and utility build-ings. Tech Tip 0471–2334P–MTDC. Missoula, MT: U.S. Department of Agriculture, Forest Service, Missoula Technology and Development Center. 8 p. Available at and to Forest Service and BLM employees on the internal Forest Service network at .

Land, Brenda. 2004. Micro-flush toilets. Tech Tip 0423–1310P–SDTDC. San Dimas, CA: U.S. Department of Agriculture, Forest Service, San Dimas Technology and Development Center. 4 p. Available at and to Forest Service and BLM employees on the internal Forest Service network at .

Land, Brenda. 2009. Vault toilet interception analysis. Tech Tip 0823–1307P–SDTDC. San Dimas, CA: U.S. Department of Agriculture, Forest Service, San Dimas Technology and Development Center. 8 p. Available at and to Forest Service and BLM employees on the internal Forest Service network at .

http://www.fs.fed.us/eng/php/library_card.php?p_num=9123%201601http://www.fs.fed.us/eng/php/library_card.php?p_num=9123%201601http://fsweb.mtdc.wo.fs.fed.us/php/library_card.php?p_num=9123%201601http://fsweb.mtdc.wo.fs.fed.us/php/library_card.php?p_num=9123%201601http://www.fs.fed.us/t-d/php/library_card.php?p_num=0471%202334http://www.fs.fed.us/t-d/php/library_card.php?p_num=0471%202334http://www.fs.fed.us/t-d/php/library_card.php?p_num=0471%202334http://www.fs.fed.us/t-d/php/library_card.php?p_num=0471%202334http://fsweb.mtdc.wo.fs.fed.us/php/library_card.php?p_num=0471%202334http://www.fs.fed.us/eng/php/library_card.php?p_num=0423%201310Phttp://www.fs.fed.us/eng/php/library_card.php?p_num=0423%201310Phttp://www.fs.fed.us/eng/php/library_card.php?p_num=0423%201310Phttp://fsweb.mtdc.wo.fs.fed.us/php/library_card.php?p_num=0423%201310Phttp://fsweb.mtdc.wo.fs.fed.us/php/library_card.php?p_num=0423%201310Phttp://www.fs.fed.us /eng/php/library_card.php?p_num=0823%201307Phttp://www.fs.fed.us /eng/php/library_card.php?p_num=0823%201307Phttp://fsweb.mtdc.wo.fs.fed.us/php /library_card.php?p_num=0823%201307Phttp://fsweb.mtdc.wo.fs.fed.us/php /library_card.php?p_num=0823%201307P

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Contact InformationContact the National Technology & Development

Program (NTDP) for additional technical information:

USDA Forest Service

National Technology & Development Program

Phone: 406–329–3978 or 909–599–1267

Email NTDP: wo_mtdc_pubs@fs.fed.us

Find electronic copies of NTDP documents on the

Internet at:

Search NTDP

Forest Service and Bureau of Land Management

employees can search NTDP documents, CDs, DVDs,

and videos on their internal computer networks at:

Search MTDC

Search SDTDC

About the AuthorKathleen C. Marks is a multi-disciplinary project

leader at the National Technology and Development

Program for the facilities and environmental compli-

ance and protection (ECAP) programs. Marks began

her U.S. Department of Agriculture, Forest Service,

career in 2010 after receiving a bachelor’s degree in

civil engineering from Montana State University in

Bozeman, MT.

Library CardMarks, K. 2013. Resources to help prevent flooding

of vault toilets in recreation sites on national forests.

1373–2314–MTDC. Missoula, MT: U.S. Department of

Agriculture, Forest Service, Missoula Technology and

Development Center. 4 p.

Vault toilet flooding is not a new problem. Concrete

vaults sometimes fill with rainwater or snowmelt,

allowing vault contents to escape. National Technol-

ogy and Development Program staff reviewed infor-

mation about vault toilet flooding. This tech tip dis-

cusses problems associated with vault toilet flooding,

offers some solutions for toilets installed in difficult

locations, and provides references for technology

and development publications about vault toilets.

Keywords: concrete, facilities, flooding, micro-flush

toilets, outhouses, safety at work, sanitation, sweet

smelling toilets, SSTs, vault toilets

program.intake@usda.govprogram.intake@usda.govhttp://www.ascr.usda.gov/complaint_filing_cust.htmlhttp://www.ascr.usda.gov/complaint_filing_cust.htmlmailto:program.intake%40usda.gov?subject=program.intake@usda.govmailto:wo_mtdc_pubs%40fs.fed.us?subject=mailto:wo_mtdc_pubs%40fs.fed.us?subject=http://www.fs.fed.us/eng/pubshttp://www.fs.fed.us/eng/pubshttp://fsweb.mtdc.wo.fs.fed.us/search/http://fsweb.mtdc.wo.fs.fed.us/search/http://fsweb.sdtdc.wo.fs.fed.us/http://fsweb.sdtdc.wo.fs.fed.us/

Resources to Help Prevent Flooding of Vault Toilets in Recreation Sites on National ForestsReviewNew TechnologyFor Areas With Extensive FloodingSummary