DOCSLIB.ORG

Backcountry Sanitation Manual Science Knows Now That the Most Fertile and Effective Manure Is the Human Manure

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Backcountry Sanitation Manual Science Knows Now That the Most Fertile and Effective Manure Is the Human Manure APPALACHIAN TRAIL CONFERENCE Backcountry Sanitation Manual Science knows now that the most fertile and effective manure is the human manure. Do you know what these piles of manure are, those carts of mud caried off at night from the streets, the frighful barrels of the nightman, and the fetid streams of subterranean mud which the pavement conceals from you? All of this is a flowering, it is green grass, it is the mint and thyme and sage, it is game, it is cattle, it is the satisfied lowing of heavy kine, it is the perfumed hay, it is gilded wheat, it is bread on your table, it is warm blood in your veins. —Victor Hugo, Les Miserables Contents Preface .............................................................................................................................................................. 5 What This Manual is About ................................................................................................................... 5 Never Apologize, Just Explain............................................................................................................... 7 Acknowledgments ........................................................................................................................................... 9 Part 1—Background of Sanitation Management ......................................................................................... 13 1—A Brief History of Northeastern Backcountry Use and Backcountry Sanitation Management ....... 15 2—The Importance of Backcountry Sanitation Management.............................................................. 17 3—The Decomposition and Composting Process .............................................................................. 22 4—Health and Safety Issues............................................................................................................... 29 Part 2 — Regulatory and Aesthetic Issues .................................................................................................. 35 5—Integrating Backcountry Sanitation and Local Management Planning .......................................... 36 6—Introduction to the Regulatory Process ......................................................................................... 37 7—The Aesthetics of Backcountry Sanitation Systems ...................................................................... 42 Part 3—Descriptions of Systems.................................................................................................................. 45 8—The Moldering Privy....................................................................................................................... 46 9—Batch-Bin Composting ................................................................................................................... 63 10—Liquid Separation in Composting Systems .................................................................................. 90 Part 4 — Installations..................................................................................................................................... 97 11—Case Studies ............................................................................................................................... 98 11.1 Moldering Privy on the A.T. at Little Rock Pond, Vermont ............................................. 98 11.2 Moldering Privy on the A.T. in Massachusetts ............................................................... 99 11.3 Appalachian Mountain Club Clivus Multrum Composting Toilet .................................. 101 11.4 Randolph Mountain Club Bio-Sun Composting Toilet.................................................. 102 11.5 At Home with the Clivus Multrum Composting Toilet ................................................... 108 11.6 Airlift Haul-Out Systems .............................................................................................. 112 11.7 Flush Toilets with Leach Field at High Mountain Huts ................................................. 112 11.8 Prototype Wood-Fired Compost Incinerator ................................................................ 115 12—The Decision Making Process ................................................................................................... 117 13—Gray Water Management in the Backcountry ............................................................................ 128 Contents, continued Appendices ................................................................................................................................................... 133 A—Glossary of Terms ....................................................................................................................... 134 B—Troubleshooting and General Composting Tips .......................................................................... 137 C—About the Organizations behind this Manual .............................................................................. 145 D—Contact List ................................................................................................................................. 149 E—Bibliography ................................................................................................................................ 159 F—Examples of Stewardship Signs .................................................................................................. 162 G—Sources of Materials for a Batch-Bin System ............................................................................. 172 H—Lightweight Outhouse Plans ....................................................................................................... 174 I—Plans for a Double-Chambered Moldering Privy .......................................................................... 181 J—Plans for a Drying Rack ............................................................................................................... 186 K—Diagram of a Washpit .................................................................................................................. 188 L—Backcountry Sanitation: A Review of Literature and Related Information ................................... 189 M—The Application of a Solar Hot Box to Pasteurize Toilet Compost in Yosemite National Park .... 198 N—Examples of Regulatory Correspondence .................................................................................. 202 O—Article from ATC Newsletter, The Register ................................................................................. 207 P—Owner-Built Continuous Composters .......................................................................................... 211 Q—Plans for a Wooden Packboard .................................................................................................. 213 PREFACE—5 Preface What This Manual is About Pete Ketcham, Field Supervisor, Green Mountain Club The ATC Backcountry Sanitation Manual addresses the management of human waste in the backcountry. Proper management of human waste protects hikers, the environment and trail maintainers. Resolving problems of backcountry sanitation is a continuous challenge for Trail clubs and land managers. This manual was created in the belief that all remote recreation areas will benefit from an expanded discussion of backcountry sanita- tion. The Appalachian Trail Conference (ATC) hopes it will offer a step up for those who operate composting systems, as well as for those Appalachian Trail (A.T.) clubs and land managers who have reached a crossroads in backcountry sanitation decisions. This manual introduces a new, simpler and often safer method of composting hu- See: Section 8, “The Moldering man waste in the backcountry—the moldering privy. It is a design that saves money Privy” in Part 3—Descriptions of and—even more importantly—labor. Whether volunteer or paid, labor has always Systems. been in short supply on the A.T. The moldering privy is suitable for the majority of sites that need better waste management than pit privies or catholes, and it is cheaper and easier to implement than other alternatives. The approaches recommended here are distilled from the experiences of several hundred people operating composting toilets and other systems that have success- fully resolved human waste problems at backcountry sites along the A.T. Primary emphasis has been placed on composting systems, because they have been the most successful in the majority of backcountry situations. However, other systems receive some attention, especially to provide comparisons with composting systems. The Green Mountain Club and the Appalachian Mountain Club began using composting systems in the late 1970s, and their systems have undergone continual evolution and improvement. Several other A.T. clubs and land managers have used different composting systems with varying success. The most successful systems are presented in this manual. 6—APPALACHIAN TRAIL CONFERENCE —BACKCOUNTRY SANITATION MANUAL If you read this manual through, you will discover a lot of repetition. This is inten- tional, because the manual is being posted on the Web, where readers may down- load only the chapters that interest them. Therefore, each chapter must be self- contained, with as much relevant information as possible. Inevitably, this leads to repetition, although we have tried to minimize it by the use of cross-references to other chapters where appropriate. The first four sections provide background for sanitation management. Section 1 covers the history of
Load more

Recommended publications
  • Leave No Trace Outdoor Skills & Ethics
    ISLE ROYALE NATIONAL PARK Leave No Trace Outdoor Skills & Ethics Leave No Trace Outdoor Skills and Ethics ISLE ROYALE NATIONAL PARK Leave No Trace Center for Outdoor Ethics November, 2004 Leave No Trace — Isle Royale National Park Skills & Ethics 1 Wildland Ethics "Ethical and moral questions and how we answer them may determine whether primal scenes will continue to be a source of joy and comfort to future generations. The decisions are ours and we have to search our minds and souls for the right answers..." "The real significance of wilderness is a cultural matter. It is far more than hunting, fishing, hiking, camping or canoeing; it has to do with the human spirit." —Sigurd F. Olson ...and so we visit wild places to discover ourselves, to let our spirits run with the graceful canoe and journey through the beckoning forests. The wilderness is good for us. It enables us to discover who we really are, and to explore who we are really meant to be. It is the nature of wild places that gives us the space to slow the pace of our lives, to becalm the storms of everyday life, to gain perspective on the things we truly value. Sigurd Olson needed wild places...they gave much to him, as they do to us—and, so, we should be eager to give back. Our favorite places— those whose forests have welcomed us, whose lakes have refreshed us, whose sunsets have inspired awe—are not ours alone. They are a treasured resource, there for the good of all who seek their own true spirit through solitude and adventure.
    [Show full text]
  • Ravalli County 4-H Horse Project Guidelines
    4-H PLEDGE I Pledge my HEAD to clearer thinking, My HEART to greater loyalty, My HANDS to larger service, And my HEALTH to better living, RAVALLI COUNTY 4-H For my club, my community, my country and my world. HORSE PROJECT GUIDELINES 2017-2018 The guidelines may be amended by the Ravalli County 4-H Horse Committee each year between October 1st and January 30th. No changes will be made from February 1st through September 30th. If any member or leader wants to request an exception to any rule in the guidelines, they must request a hearing with the Ravalli County 4-H Horse Committee. Updated December 2017 Table of Contents RAVALLI COUNTY 4-H HORSE COMMITTEE CONSTITUTION ............................................................................................................................. 3 ARTICLE I - Name ............................................................................................................................................................................................. 3 ARTICLE II - Purpose ........................................................................................................................................................................................ 3 ARTICLE III - Membership ............................................................................................................................................................................... 3 ARTICLE IV - Meetings ....................................................................................................................................................................................
    [Show full text]
  • CWLT Student Guide
    Cold Weather Leader Training STUDENT GUIDE Northern Tier National High Adventure Boy Scouts of America Northern Tier National High Adventure Cold Weather Leader Training Student Guide Table of Contents About Okpik and CWLT ................................................................................................................ 4 How Do We Prepare Mentally and Physically? ............................................................................. 5 What are the risks? (Risk Advisory) ............................................................................................... 6 How do I prevent problems? ........................................................................................................... 7 General policies and information .................................................................................................... 7 How do I get there? ......................................................................................................................... 8 What do I need to pack?.................................................................................................................. 9 Patches and Program Awards ....................................................................................................... 12 Feed the Cold (a pre-CWLT assignment) ..................................................................................... 13 Sample Course Schedule (subject to change) ............................................................................... 14 Cold Weather Camping................................................................................................................
    [Show full text]
  • Composting Toilets: a Review* of Their Use in Public Venues in the U.S
    Composting Toilets: A Review* of Their Use in Public Venues in the U.S. (Updated November 8, 2016) Introduction :::::::::::::::::::::::::::::: 1 The Crystal Springs Golf Course :::::::::: 5 Manufacturers :::::::::::::::::::::::::::: 1 El Pol´ınSpring ::::::::::::::::::::::::::: 6 Buildings at the Vermont Law School ::::: 2 San Jose Environmental Innovation Center7 The Bronx Zoo Eco-Restroom ::::::::::::: 4 Frequently asked questions :::::::::::::::: 7 The University of Vermont :::::::::::::::: 5 Concluding remarks ::::::::::::::::::::: 11 Installations in California ::::::::::::::::: 5 Introduction Mention \composting toilet", and most people will think of something suitable for a summer cabin or a rural residence off the grid|a kind of classy outhouse|surely not something suitable for installation in an urban environment. As one person has remarked, flush toilets are the accepted social standard. The idea of collecting human excrement in a basement composting bin does not exactly square with the modern paradigm of gracious living. There is, however, more to the story. In what follows, we describe six composting toilet installations of varying types, currently installed for public use in locations in the United States, including three in California. We consider only those for institutional, industrial, municipal and commercial venues, i.e., those for which maintenance can be assured. We do not consider composting toilet installations for residential use. In our descriptions, we include comments by administrators, architects and users. As we shall see, every one of these six installations is positively viewed. We also include a section on frequently asked questions, including discussions of costs and possible legal barriers. Manufacturers: Clivus Multrum is the leader A comprehensive list of manufacturers of composting toilets is available as a pdf that may be downloaded from http://www.susana.org/en/resources/library/details/876.
    [Show full text]
  • The Cultural and Environmental Unsoundness of the Chinese Public Squatting-Type Toilet: a Case Study Toward a Sustainable Excreta Treatment System
    Environ. Eng. Res. 2014 March,19(0), 0-0 Research Paper http://dx.doi.org/10.4491/eer.2014.19.0.0 pISSN 1226-1025 eISSN 2005-968X In Press, Uncorrected Proof The Cultural and Environmental Unsoundness of the Chinese Public Squatting-type Toilet: A Case Study toward a Sustainable Excreta Treatment System Jin-Soo Chang Molecular Biogeochemistry Laboratory, Biological & Genetic Resources Institute (BGRI), Hannam University (Jeonming), 505 Inno-Biz Park, 1646 Yuseong-daero, Yeseong-gu, Daejeon 305-811, Republic of Korea Abstract The inconvenient truth of sustainable public squat toilet culture varies among nationalities. According to the adequate environmental management in Yanbian Korean Autonomous Prefecture (YKAP), northern China, this culture may be comfortable to the people of China, yet uncomfortable to the non-Chinese. We conducted a series of field surveys and individual interviews (Chinese n = 1000 and non-Chinese (foreign visitors) n = 100) on several aspects of the public squat toilet: structural properties, waste disposal methods, important factors, and overall satisfaction level. The significant factors in response to the public squat toilets were cleanliness, odor, toilet paper, temperature, soap, other facilities, and presence of cubicles. These factors should be the policy priorities of local government. In addition, 66.2% of Chinese and 91% of foreign visitors desired type E toilets (two full-height partition walls per cubicle, with a door). The results illustrate the nature of a sustainable and aesthetic approach to the culturally and environmentally sound management of various types of public squat toilet in YKAP. The government needs to focus on the future-oriented and excreta treatment management of the sustainable toilet culture for the residents of, and visitors to, YKAP.
    [Show full text]
  • GRUNDY COUNTY 2019 All American Fair
    GRUNDY COUNTY 2019 All American Fair Sponsored by the Grundy County Agricultural Society Recipient Grundy County Fair website: www.grundycountyfair.com Grundy County Fair 4-H & FFA Entries: http://grundy.fairentry.com Grundy County Fair Open Class Entries: http://grundyopen.fairentry.com Association of Fairs 2014 Blue Ribbon Fair Award Grundy County Fairgrounds Grundy Center, Iowa The Fairgrounds are on the south edge of town. Enter the Fairgrounds on 4th Street or 1st Street. 21→ 1 15 16 3 2 5 19 18 14 20 4 6 13 5 7 8 12 9 11 10 Parking is allowed on the grass area along the fence line, to the North of the main fairground road and on the south side of the fairgrounds Buildings 11. Wheelock Building 1. Building #1 12. Beef Barn 2. Shelter 13. Bucket Calf Barn 3. Upper Bathrooms 14. Alumni Building 4. Swine Barn 15. Exhibit Building & Bathrooms 5. Sheep Barn 16. Shelter 6. Upper Show Arena & 4-H Office 17. Open Class 7. Dairy Barn 18. Gazebo 8. Poultry Barn 19. Grandstands 9. Rabbit Barn 20. Band & Beer Garden 10. Horse Arena 21. New Campgrounds TABLE OF CONTENTS: FAIR SCHEDULE…………………………………………………………………………………………………………………………...…. 4 FAIR OFFICIALS………………………………………………………………………..……………………………………………..………. 7 GENERAL INFORMATION Alcohol Policy …………………………………………………………………………………………………………..………… 9 Lost & Found ……………………………………………………………………………………………………………………... 9 Complaint Procedure………………………………………………………………………………………….………………. 9 Grundy County 4H & FFA Show Premiums………………………………………………………………………….. 9 Camping & Overnight Information…………………………………………………………………………..………..
    [Show full text]
  • Early Californios Skills of the Rancho General Rules
    Early Californios Skills of the Rancho General Rules • Horses must be ridden in a hackamore, two-rein, or straight up in the bridle. • Hackamores must be rawhide or rope cores with no metal or cable used in their construction. • Horses may be shown in the hackamore as 4 year olds and older without penalty in roping and stockmanship events. • A horse 7 years or older shown in a hackamore in the stock horse will incur a ½ point penalty for every year over the age of 7 in the stock horse class. • The two-rein may only be used on horses over five years old with a fully set mouth (all teeth are in) with leather curb straps only. No tie downs, running rings or gimmicks will be allowed. • The sock horse competition will be judged throughout the event. Those horses must be shown in the same equipment in all their events. • Rider may use two hands on under bridle rein only when needed. The use of two hands on bridle reins will result in major penalties or disqualification at judge’s discretion. • Bridle horses must be ridden in Californio style bridles. No broken or hinged mouthpieces are allowed. • Romal reins with chains and neck or get-down ropes are required. • To lead a horse by bridle reins at any time during the competition will result in major penalties or disqualification at judge’s discretion. • The use of a spade bit is encouraged, as this is a cornerstone of the Californio bridle horse. A ½ point will be awarded to each member of a team whose horse comfortably works in a spade bit.
    [Show full text]
  • AUCTION Business News Barrow
    VOLUME 35, NUMBER 6 JULY 8, 2010 FREE THE WEEKLY NEWS & LIFESTYLE JOURNAL OF MT. WASHINGTON VALLEY Living History In Albany: A Civil War Living History Encampment, featuring the 5th Massachusetts Battery, Light Artillery Army Of The Potomac, Inc., came to the Russell-Colbath Historic Homestead on the Kancamagus Highway in Albany on July 3 and 4.… A6 40 Years On Stage: The Mount Washington Valley Theater Company begins its 40th season with ‘The Music Man’ and the theater com- pany plans to engage, entertain and excite audiences this summer ... A7 Tin Mountain Nature Corner: Brake for moose, it could save your life! Learn fun facts about the third largest land animal in North America… A 28 A SALMON PRESS PUBLICATION • (603) 447-6336 • PUBLISHED IN CONWAY, NH Page Two Can-Am Jericho ATV Festival A new kind of mud madness and family fun hen Jericho come. Any ATV or trail bike Mountain State that will be used only at the Park in Berlin event — that is, within Jericho became New Mountain State Park, the Cross- Hampshire’sW newest State Park, City Trail and the Success Trail it was designed to provide the — will not need a NH registra- first network of all-terrain vehi- tion during the Festival. We cle trails on state land in New hope that the event will spur rid- Hampshire. Now, with 50-plus ers to register their ATVs in miles of scenic trails and a new New Hampshire in the future, mud pit, the 7500-acre Park is as those registration dollars will set to host the Cam-Am Jericho directly impact future develop- ATV Festival on Saturday, July ment in the Park.” 10, from 8 a.m.
    [Show full text]
  • Together for Waterless Toilets
    Together for waterless toilets This years biggest news, though the smallest toilet. You can read all about our tiny master on page 12 and 13. Separett 2021 Intro ”Our vision is to contribute to a higher quality of life for the many” This broschure has been created with accuracy. Products may differ slightly from image and reality. We reserve the right to make any product changes regarding appearance and content as well as errors in text and images 2 3 Intro Separett 2021 The journey towards hygenic toilet solutions Over 2,4 million people are at the moment not having www.separett.com access to a toilet. The result of this is the every year death of Look in to our blogg for thousands of adults and children. The contribution of interesting articles and Separett being able to provide toilet solutions that can give other fun reading people a higher quality of life all over the world is very important. We want to accelerate the development of hygenic toilet solutions for the population of the world. That is the mission of Separett. And we do it by developing sewage- and waterless toilets. It is a long journey I want to improve that is being guided by our Separett AB hearts more than our economical goals. It is only together that we can at Youtube. reach the goals being set by United nations regarding the security for Follow our Youtube channel for inspiration and advices safe water and sanitation around the world. As a part of the humanity and its progress towards sanitary toilet solutions are we at Separett together with a non-profit organisation sending toilets to areas in Peru where the need of toilet solutions are great.
    [Show full text]
  • Technology Review of Urine-Diverting Dry Toilets (Uddts) Overview of Design, Operation, Management and Costs
    Technology Review of Urine-diverting dry toilets (UDDTs) Overview of design, operation, management and costs As a federally owned enterprise, we support the German Government in achieving its objectives in the field of international cooperation for sustainable development. Published by: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH Registered offices Bonn and Eschborn, Germany T +49 228 44 60-0 (Bonn) T +49 61 96 79-0 (Eschborn) Friedrich-Ebert-Allee 40 53113 Bonn, Germany T +49 228 44 60-0 F +49 228 44 60-17 66 Dag-Hammarskjöld-Weg 1-5 65760 Eschborn, Germany T +49 61 96 79-0 F +49 61 96 79-11 15 E [email protected] I www.giz.de Name of sector project: SV Nachhaltige Sanitärversorgung / Sustainable Sanitation Program Authors: Christian Rieck (GIZ), Dr. Elisabeth von Münch (Ostella), Dr. Heike Hoffmann (AKUT Peru) Editor: Christian Rieck (GIZ) Acknowledgements: We thank all reviewers who have provided substantial inputs namely Chris Buckley, Paul Calvert, Chris Canaday, Linus Dagerskog, Madeleine Fogde, Robert Gensch, Florian Klingel, Elke Müllegger, Charles Niwagaba, Lukas Ulrich, Claudia Wendland and Martina Winker, Trevor Surridge and Anthony Guadagni. We also received useful feedback from David Crosweller, Antoine Delepière, Abdoulaye Fall, Teddy Gounden, Richard Holden, Kamara Innocent, Peter Morgan, Andrea Pain, James Raude, Elmer Sayre, Dorothee Spuhler, Kim Andersson and Moses Wakala. The SuSanA discussion forum was also a source of inspiration: http://forum.susana.org/forum/categories/34-urine-diversion-systems-
    [Show full text]
  • JOE BARKSHIRE ESTATE AUCTION Sante Fe Morris Morris 16.5” 15.5” 15.5” 13” 13” 12” Saturday, October 29Th, 2016 9:00 A.M
    James Morris Longhorn omas JOE BARKSHIRE ESTATE AUCTION Sante Fe Morris Morris 16.5” 15.5” 15.5” 13” 13” 12” Saturday, October 29th, 2016 9:00 A.M. • Family Living Center • Mt Expo Park 400 3rd Street North • Great Falls, MT Simco Longhorn Buck Steiner Blue River Morris Morris 15” 15.5” 14.5” 15.5” 15” 12” Kelly Longhorn, 79” Crockett Renalde Brass Sleigh Bells Longhorn, 42” Buermann Spanish Style Mexican Buermann Kelly Don Ricardo Horsehair Lap Robe Ft. Shaw Mailboxes Rawhide Reins Rawhide Romal Sliester US Calvary W. T. Gilmer Silver Mtd. Spur Straps Ario Invoice Morris Saddlery, 12”, junior barrel saddle, stamped & carved, Rancho Grande Magdalena & Son, 13.5”, watusi swells, ta- Rawhide reins with romal, Santa Inez type, excellent! SADDLES rawhide horn, padded green seat, rhinestone silver con- pederos COWBOY COLLECTIBLES Rawhide roping reins with romal, four strand braid chos, brand new Rex Newell, Coleman, TX, 13”, bear trap Mexican silver /copper inlaid curb bit in braided leather Morris Saddlery, Caballo, NM, 15”, association, at plate dou- Morris Saddlery, 16”, roping saddle, 15.5”, double rig S.D. Myres, El Paso, 14”, stock saddle, double rig Vintage U.S. postal mail boxes, from Ft. Shaw, MT Post Oce, headstall and silver mtd bit ble rig, rough out, rawhide bound cantle & horn, brand new Morris Saddlery, 16”, Roping saddle, 15.5”, double rig Sante Fe, 13.5” barrel saddle, rawhide horn 3 sections, 33”w, 25”w & 7”w, all 47”h x 11”d, all metal Buermann silver mtd spade bit w/ braided leather headstall & reins Morris Saddlery, 13”,
    [Show full text]
  • Sanitation Options
    MIT OpenCourseWare http://ocw.mit.edu 11.479J / 1.851J Water and Sanitation Infrastructure in Developing Countries Spring 2007 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. On-site Sanitation Brian Robinson and Susan Murcott Week 12 - MIT 11.479J / 1.851J Water and Sanitation Infrastructure in Developing Countries Mass. Institute of Technology May 8, 2007 On-site Sanitation • Sanitation ladder: options in sanitation • Ecological Sanitation • Case Study: Ecosan in Kenya Improved sanitation • connection to a public sewer • connection to septic system • pour-flush latrine • simple pit latrine • ventilated improved pit latrine The excreta disposal system is considered “adequate” if it is private or shared (but not public) and if it hygienically separates human excreta from human contact. "Not improved“ = service or bucket latrines (where excreta are manually removed), public latrines, latrines with an open pit. Sanitation “Ladder” Technology Hygiene 1. Open defecation, “flying toilet” 2. “Cathole” burial 3. Pit latrine 4. VIP 5. EcoSan 6. Pour-flush 7. Water-sealed toilets + neighborhood wastewater collection 8. Water-sealed toilets + neighborhood wastewater collection + treatment 1. No Poop sanitation *S. Murcott (T.P.) 2. “Cathole” burial Sanitation “Ladder” Technology Hygiene 1. Open defecation, “flying toilet” 2. “Cathole” burial 3. Pit latrine 4. VIP On-site sanitation 5. EcoSan 6. Pour-flush 7. Water-sealed toilets + neighborhood wastewater collection 8. Water-sealed toilets + neighborhood wastewater collection + treatment 3. Pit latrine – with pit Drainage? 3. Pit Latrine, No Pit 4. Ventilated Fly screen improved Air (ventilation) pit latrine (VIP) Vent pipe Seat cover A dry latrine system, with a screened vent pipe Pedestal to trap flies and often Pit collar Cover slab (May be extended to with double pits to base of pit in poor allow use on a ground conditions) permanent rotating basis.
    [Show full text]