Ecolodge Engineering in Eastern and Southern Africa

Master’ Thesis in Environmental Engineering and Management

Bauhaus Universität Weimar

Examiner: Dr. Prof. Werner Bidlingmaier

Author: Chris Rollins, B.S. 4500 Business Park Boulevard, Suite C-10 Anchorage, Alaska 99503 USA +1-907-351-2423 cebengineering@gmail.com

CONTENTS Introduction to Ecolodges ...................................................................................................................... 4

Sustainable tourism and economic development in poor countries ..................................................... 5What is an ecolodge? ......................................................................................................................... 6Ecolodges and Community Based Organizations ............................................................................... 7The ecolodge ‘problem’ ...................................................................................................................... 7Ecolodge rating systems .................................................................................................................... 8Role of engineering in ecolodge planning, design, and implementation .............................................. 9Africa ecoregions ............................................................................................................................. 10

Planning and Project Management ...................................................................................................... 14Feasibility Study and Financial/Marketing Plan ................................................................................. 14Master Plan ...................................................................................................................................... 15Environmental Impact Assessment .................................................................................................. 16Community Involvement ................................................................................................................... 18Project Management ........................................................................................................................ 19

Performance Assessment .................................................................................................................... 21Embodied Energy ............................................................................................................................. 21Life Cycle Assessment ..................................................................................................................... 22Design for Deconstruction ................................................................................................................ 22‘Buy Local’ ........................................................................................................................................ 23Monitoring and Evaluation ................................................................................................................ 24

Construction and Materials .................................................................................................................. 26Material transport ............................................................................................................................. 26Construction impact .......................................................................................................................... 27Season and storm water control ....................................................................................................... 27Tools ................................................................................................................................................ 28Water and pumping .......................................................................................................................... 28Generators ....................................................................................................................................... 29Materials and Techniques ................................................................................................................ 30

Water Supply and Purification .............................................................................................................. 40Objectives of water treatment ........................................................................................................... 42Water testing .................................................................................................................................... 45Water sources .................................................................................................................................. 45Pretreatment .................................................................................................................................... 47Sedimentation and Coagulation/Flocculation .................................................................................... 47Filtration ........................................................................................................................................... 48Disinfection ...................................................................................................................................... 49Desalinization ................................................................................................................................... 51

Waste Water Treatment ....................................................................................................................... 54Grey water recycling ......................................................................................................................... 57Ecosanitation .................................................................................................................................... 59Composting toilets ............................................................................................................................ 60Biogas .............................................................................................................................................. 62Septic tank ....................................................................................................................................... 65

Grease trap ...................................................................................................................................... 67Subsurface wastewater infiltration system ........................................................................................ 68Package plants ................................................................................................................................. 68Intermittent sand filters ..................................................................................................................... 69Constructed wetland ......................................................................................................................... 70Percolation test ................................................................................................................................ 72

Solid Waste Management .................................................................................................................... 73Segregation Area ............................................................................................................................. 73Composting ...................................................................................................................................... 74Incineration ...................................................................................................................................... 74Landfilling ......................................................................................................................................... 76Removal ........................................................................................................................................... 76

Hot Water Supply ................................................................................................................................. 77Solar ................................................................................................................................................ 78Tankless water heater ...................................................................................................................... 82Electric ............................................................................................................................................. 83Wood fired boiler .............................................................................................................................. 83

Electrical System ................................................................................................................................. 86Calculating load ................................................................................................................................ 86Generator ......................................................................................................................................... 87Photovoltaics .................................................................................................................................... 90Wind ................................................................................................................................................. 92Microhydro ....................................................................................................................................... 93Hybrid System .................................................................................................................................. 96

Glossary .............................................................................................................................................. 98

Appendices ........................................................................................................................................ 107Planning ......................................................................................................................................... 107Site Selection Matrix ....................................................................................................................... 111Materials energy costs ................................................................................................................... 112Project schedule ............................................................................................................................. 113Tool list ........................................................................................................................................... 114Generator Efficiency ....................................................................................................................... 115Concrete Mixes by Volume and Use .............................................................................................. 116CEB Block Cost Comparison .......................................................................................................... 117Erosion Control Measures .............................................................................................................. 118Biogas Digester .............................................................................................................................. 120Grease Trap ................................................................................................................................... 121Septic Tank .................................................................................................................................... 121Water Tank .................................................................................................................................... 122

Bibliography ....................................................................................................................................... 123

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INTRODUCTION TO ECOLODGES

This document intends to elaborate, analyze, and recommend best practices for the technical components of remote tourist facilities in the eastern and southern regions of Africa, or so-called ‘ecolodges.’ A remote lodge with a high level of service can be described in many ways, as a village, an economy, a mass balance equation, or even a machine, and a borrowing of some terminology from various fields allows one to best describe and dissect the thing; likewise, terms from different disciplines are necessary to attempt optimization, including life-cycle energy analysis, financial cash flow, the water cycle, and project management.

Photo 1 Bua River Lodge, Malawi.

Photo 2 Kizingo Ecolodge, Lamu.

Photo 3 Lukwe Ecocamp, Malawi.

Photo 4 Tongole Lodge, Malawi.

Ecotourism is defined as “Responsible travel to natural areas that conserves the environment and improves the welfare of local people”1

1 The International Ecotourism Society, TIES Global Ecotourism Fact Sheet, 2006.

. Ecotourism was first described in 1983 by the Mexican Architect Héctor Ceballos-Lascuráin, and since that date it has steadily become an ever larger share of the international tourism market. Although ecotourism is a relatively new part of the tourism industry, it is

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perceived as a viable mechanism for future development for poor communities in many parts of the world that otherwise have few economic opportunities due to poor infrastructure, remoteness of location, and lack of local skills or high value products. This is particularly true in Africa, where many other economic development strategies have failed, although the overall economic impact of ecolodges compared to other rural economic schemes will not be investigated here.

The term ‘ecolodge’ is a still imprecise term, but it can generally be described as a remote tourist facility which promotes ecotourism. Because such facilities are unregulated and there is not yet an internationally recognized accreditation scheme, many facilities appropriate the word as a marketing tool while utilizing few, if any, of the qualities and processes of an ecolodge. Indeed, the creation of a true ecolodge in a remote area can be very difficult and expensive, due to the extra planning, community involvement, infrastructure, and monitoring required to minimize negative impacts while promoting positive benefits.

For the purpose of this exercise, an ecolodge will be described as ‘remote,’ meaning away from an improved road, and without electrical or water and wastewater mains connection. Such facilities may or may not have communications access, including mobile phone and internet network, which will also be investigated. In researching this text, some lodge facilities are given as examples for a particular facet though they may not be ‘remote’ as defined; for example, it is common for a facility to have electrical mains without a water and wastewater connection.

This thesis will explore the ecolodge phenomenon from the engineering perspective, including standards and evaluation methods; planning and design; project management and construction; structural, mechanical, and electrical systems; and operations. Although no perfect ecolodge does exist, or possibly can exist, an assortment of lodge components will attempt to convey real world examples of exemplary methods and systems. Furthermore, a series of tools for ecolodge engineering, including life cycle costing, engineering equations and tabular examples, and specific products and techniques, is included to guide the reader on technical decision making for ecolodge planning and construction.

Sustainable tourism and economic development in poor countries

The UN World Tourism Organization estimates that international tourism generated € 642 billion ($944 billion) in 20082, and in 2007, receipts for developing countries (low income, lower and upper middle income countries) amounted to US$ 319 billion, and was the largest source of foreign exchange earnings in a majority of Least Developed Countries3

Sustainable Tourism has the following features, according to the Cape Town Declaration on Responsible Tourism

. A part of this sector defined as ‘Sustainable Tourism’ is identified by the World Tourism Organization as a means to alleviate poverty (especially for people in remote areas living on less than $1 per day), conserve the environment, and create jobs.

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• minimizes negative economic, environmental, and social impacts

(features with importance to this document are in italics):

• generates greater economic benefits for local people and enhances the well-being of host communities, improves working conditions and access to the industry

2 www.unwto.org 3 www.unwto.org 4 www.icrtourism.org

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• involves local people in decisions that affect their lives and life chances • makes positive contributions to the conservation of natural and cultural heritage, to the

maintenance of the world’s diversity • provides more enjoyable experiences for tourists through more meaningful connections with local

people, and a greater understanding of local cultural, social and environmental issues • provides access for physically challenged people and • is culturally sensitive, engenders respect between tourists and hosts, and builds local pride and

confidence.

The UN World Tourism Organization “Sustainable Tourism – Eliminating Poverty” (ST-EP) program has identified 7 steps by which the poor can benefit directly through tourism5

• Employment of the poor in tourism enterprises

(features with importance to this document are in italics):

• Supply of goods and services to tourism enterprises by the poor or by enterprises employing the poor.

• Direct sales of goods and services to visitors by the poor (informal economy) • Establishment and running of tourism enterprises by the poor - e.g. micro, small and medium

sized enterprises (MSMEs), or community based enterprises (formal economy) • Tax or levy on tourism income or profits with proceeds benefiting the poor • Voluntary giving/support by tourism enterprises and tourists • Investment in infrastructure stimulated by tourism also benefiting the poor in the locality, directly

or through support to other sectors

What is an ecolodge?

According to the International Ecolodge Guidelines, Hitesh Mehta, a leading ecolodge architect, states that an ecolodge can be defined as ‘an accommodation facility that displays at least five of the following criteria’6

• Helps in the conservation of the surrounding flora and fauna.

(features with technical importance to the engineer are in italics):

• Endeavors to work together with the local community • Offers interpretive programs to educate both its employees and tourists about the surrounding

natural and cultural environments • Uses alternative, sustainable means of water acquisition and reduces water consumption • Provides for careful handling and disposal of solid waste and sewage • Meets its energy needs through passive design and renewable energy sources • Uses traditional building technology and materials wherever possible and combines these with

their modern counterparts for greater sustainability. • Has minimal impact on the natural surroundings during construction • Fits into its specific physical and cultural contexts through careful attention to form, landscaping

and color, as well as the use of vernacular architecture • Contributes to sustainable local community development through education programs and

research. 5 ST-EP "Tourism and Poverty Alleviation: Recommendations for Action" 6 Mehta, International Ecolodge Guidelines, pg. 5

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An ideal ecolodge might thus be one that incorporates more than five, or even all, of these criteria. Such a facility would have minimum electricity, heat, refrigeration, and waste requirements, and it would minimize other impact on the surroundings such as noise or emissions. Indeed, this could describe many remote villages in Africa where the residents have no power, refrigeration, or hot water (an exception is cooking, which is typically performed with charcoal or other emissions intensive and unreplenished biomass material).

Some ‘cultural village’ tourism complexes do exist, and they are becoming more common: examples include the Kawaza Cultural Village near Mfuwe, Zambia, Kumbali Cultural Village in Lilongwe, Malawi, or the Mida Creek Ecocamp near Watamu, Kenya. However, they are a very small part of the total ecolodge market, and more typical is a higher end facility with more complex cuisine, hot showers, and cold beer. Cultural villages do exemplify the community element of ecolodge operation, which should be integral to any remote establishment, whatever the drink temperature.

Ecolodges and Community Based Organizations

An outgrowth of this emphasis on the local community in ecotourism and ecolodge operation is the inclusion of Community Based Organizations (CBO’s) in many such businesses, some of which are majority or wholly owned by local communities. Community Based Ecotourism is a tourism concept where “the local community has substantial control over, and involvement in, its development and management, and a major proportion of the benefits remain within the community.”7 This can benefit the community through sustainable livelihood (i.e. job creation), to involve the community more actively with conservation (the ‘poacher to safari guide’ paradigm), and to generate a positive relationship between the community and protected areas8

The ecolodge ‘problem’

. Indeed, in Africa the establishment of many protected areas required the expropriation of local peoples, destroying their livelihoods and leaving their descendants destitute and resentful (including, for example the gazetting of Tsavo East National Park in Kenya, which displaced the elephant hunting tribe of the Garyama people, who both lost their land and their historical livelihood in 1952); in this light, a CBO can be considered a modern means to repair a severed relationship between a particular geography and its former inhabitants.

From an engineering perspective, an ecolodge presents a unique opportunity to promote the best of local architectural and construction practices as well as minimal impact water, mechanical, and power systems. However, the necessity to provide a luxurious visitor experience can often conflict with this philosophy, and therein lays the greatest technical difficulties for these endeavors. A holistic solution to this is typically not cheap, and often combines the latest in high technology (for example photovoltaic energy generation coupled with low energy Light Emitting Diode (LED) lighting) with much simpler and inexpensive solutions (such as constructed wetlands for water polishing after rudimentary treatment).

While early ecolodges in Costa Rica and Central America catered to the backpacker-style tourist comfortable with basic amenities such as cold showers or paraffin lamps, a newer marketing strategy has recently attracted the wealthier visitor to such destinations. This has resulted in the phenomenon of the ‘luxury ecolodge’ which still purports to adhere to the principles of sustainable tourism while charging

7 Guidelines for Community Based Ecotourism Development, WWF International, 2001, pg. 2 8 Guidelines for Community Based Ecotourism Development, WWF International, 2001, pg.4

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$400-2000 per night and providing visitors everything from heated plunge pools to high speed internet. While one can easily dismiss such trappings as counter to the ecolodge philosophy, in the tourism market they are common and cannot be ignored. Rather, an attempt should be made to lessen the impact of whatever elaborate systems are demanded by the client. In the future, perhaps a stringent international ecolodge rating system will resolve this apparent disparity.

Ecolodge rating systems

Because of the recent ubiquity of ecotourism and the ease with which any lodge operator can appropriate the term ‘ecolodge’ for marketing purposes, several organizations throughout the world have established ecolodge rating schemes for local or international projects. These groups include the Costa Rican Certification for Sustainable Tourism (CST), the Australia EcoCertification (formerly the Nature and Ecotourism Accreditation Program, or NEAP), the Ecotourism Society of Kenya (ESOK) EcoRating Scheme, the Namibia EcoAward, the Botswana Ecotourism Best Practices Guidelines Manual, and the World Travel and Tourism Council’s Green Globe 21 (GG21) international standard.

While much of the evaluation criteria in these schemes is proprietary and not disclosed publicly (perhaps to avoid lodges trying to ‘game the system’), it is likely that in the future a transparent and international system will be established which plainly ranks various options for lodge performance and systems. Until that time, the various systems can be used as general guide for the designer undertaking an effort at minimal environmental impact.

The Kenya Forestry Service has a concise approach to Ecolodge evaluation9

1. Is there a written policy regarding the environment and local people?

:

2. What is the single contribution to conservation or local people that has been put in place? 3. How is the contribution to conservation and local communities measured? 4. How many local people are in employment and what percentage of this total is in management? 5. What has specifically been done to help protect the forest, environment and support

conservation and which local charities have been involved? 6. What percentage of produce and services are sourced from within 25 km of the facility? 7. How is the treatment of waste handled – effluent, heating, solid waste etc? 8. What information and advice is provided to tourists and visitors on the forest, the local cultures

and customs? 9. Are local guides employed at the facility? 10. What guidelines and methods are put in place on how visitors can interact and get involved in

worthwhile ways and projects on forestry and with local communities and conservation?

The Ecotourism Society of Kenya uses the following open guideline10

1. Protecting, conserving and investing in the environment

:

2. Minimizing & reducing wastes 3. Preventing pollution 4. Encouraging linkages with local communities 5. Responsible use of resources such as land, water, energy, culture etc

9 10 ways to tell if an Ecolodge is a really an Ecotourist facility 10 Ecotourism Kenya website

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6. Education to tourists

The Botswana Ecotourism Best Practices Guidelines Manual contains the following guidelines11

1. Use of local construction materials

:

2. Employment of local residents to operate and in some cases manage the facility 3. Integration of water and energy conservation technologies 4. Participation and involvement with local communities in various aspects of the visitor experience 5. A portion of profits are returned to community and conservation projects 6. Use of waste water treatment techniques and recycling 7. Use of various waste management schemes including composting, recycling, etc. 8. Use of fresh food which is purchased locally and is typically organic

Role of engineering in ecolodge planning, design, and implementation

Based on these premises, the engineer has three primary technical inputs unique to an ecolodge facility, in addition to the normal engineering requirements of planning, structural and mechanical systems design, construction observation, project management, and cost estimating/scheduling:

• Lodge materials and construction methods evaluation • Lodge systems, energy inputs, and wastes minimization • Lodge operation and monitoring standards

Lodge materials include the selection of materials for foundations, walls, doors and windows, and roof, as well as design features to minimize impact on the surrounding area. Lodge construction input requires minimal impact on surrounding areas during the construction operations in terms of noise, emissions, erosion, and siltation. Construction technique is also important from the technical perspective, as the use of manual labor in place of power tools and machinery can both facilitate increased skill in the local community and reduce noise and emissions. On the other hand, though, it can result in greater total impact to the site due to increased number of people on site (and the requisite cooking, washing, and bathing), as well as lower construction quality.

Lodge systems include electricity, water supply, water purification, hot water, waste water, solid wastes, cooking, transport, and communications. Energy input for each of these is a combination of loads, efficiencies of the system, and the type of energy source, whether solar, biomass, or petroleum. Wastes criteria are a combination of reduction of waste production, on site waste processing, and waste removal in sensitive areas.

Lodge operation is a combination of the previous inputs with the added complexity of dynamic use while the lodge is running. This will require periodic technical review to actually quantify how efficiently the lodge is operating according to visitor numbers, and to identify problem areas or improvements. Processes to monitor include water usage, operating costs, waste production, transportation fuel quantities, and efficiency changes during seasonal variation in lodge occupancy, solar gain, water supply, and ambient temperature.

11 Ecotourism Best Practices Guidelines Manual, pgs. 14-15.

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Africa ecoregions An ecoregion is defined by the World Wildlife Fund as “a large unit of land or water containing a geographically distinct assemblage of species, natural communities, and environmental conditions.” Additionally, these natural communities:

• share a large majority of their species and ecological dynamics; • share similar environmental conditions, and; • interact ecologically in ways that are critical for their long-term persistence.

Eastern and Southern Africa contains the following biomes:

• Temperate coniferous forests • Temperate broadleaf and mixed forests • Montane grasslands • Temperate grasslands, savannas, and shrublands • Mediterranean scrub • Deserts and xeric shrublands • Tropical and subtropical dry broadleaf forests • Tropical and subtropical grasslands, savannas, and shrublands • Tropical and subtropical moist broadleaf forests • Flooded grasslands

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Figure 1 Copyright 2005, Dr. Jean-Paul Rodrigue, Hofstra University, Dept. of Economics & Geography

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For the purpose of this document, the following three main categories are divided into five ‘typical’ sites for ecolodge development:

• Terrestrial (land) o Mountain o Savannah o Desert

• Freshwater o Lake o River

• Marine

Mountain

Mountain areas with tourist facilities are very common and include the Nyika and Zomba Plateaus in Malawi; the Volcanoes region of Uganda, Rwanda, and DRC; Mt. Kenya and Mt. Kilamanjaro; and the Drakensburg in South Africa. Mountains enjoy perhaps the most favorable conditions for ecolodge development. The topography typically means increased rainfall, and this rain can be collected such that gravity delivery and distribution is possible both to and within the lodge. Borehole water may be seasonal, depending on geology of the area. Wind power may be viable at the right location, and very small scale hydro power (i.e. ‘pico-hydro’) can also be employed, though this is often considerably expensive compared to wind or solar PV.

• PV may not be viable due to cloud cover • Wind may be an option • Possibilities for hydropower, though this is expensive • Water sources may be available with spring box + gravity feed

Savannah

Savannah or plains areas include the Serengeti and Mara in Tanzania and Kenya; the Kalahari of Botswana and the Karoo of South Africa. Savannah is the far largest area by type in this part of the continent, and lodges may vary tremendously in individual geographical and climatic character.

• Water from borehole and rooftop collection • PV + wind typical for power generation

Desert

Desert lodges, such as those of Namibia, will have unique constraints:

• Water will be from boreholes, and this may require energy intensive pumping and treatment. • Traditional construction materials, such as wood and thatch may be unavailable locally and may

shrink significantly in arid conditions, although rotting will not be a problem. • Heating/cooling loads may require large power sources (i.e. diesel generators)

Lake

Lakes include the Great Lakes (Victoria, Tanganyika, Malawi, Kivu) as well as smaller bodies of water. Lakeside lodges enjoy a perennial water source, though this may require seasonal or year round

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flocculation. This water must be pumped, requiring electrical inputs. Electricity options include PV and wind, usually in combination due to seasonal changes in wind speed.

• Water purification from lake is typically coarse filtering, flocculation, filtering, UV or chlorination • Boreholes may be difficult to install and maintain in sand • Wind power may be viable • Wastewater treatment is important before discharge

River

River lodges are found within other biomes (i.e. savannah, mountain, desert), and also enjoy a perennial water source. River water tends to vary considerably in quality throughout the year, and this may place high demands on the technical skill of the operations personnel. In many cases, a borehole may be a preferred option to river water filtration due to the lower maintenance of the system, despite the higher initial cost.

• Water purification from river may be poor due to high turbidity in the rainy season

Marine

Marine lodges are to be found throughout the Indian Ocean coast. These vary from the basic to the massive and in both size and service, but all share a critical need: fresh water. Some sites enjoy a fresh water ‘lens’ which floats on a salt layer due to its lower relative density. Such locations are rare, and should be actively conserved so as to not destroy the balance. In many cases, desalination is the only option if the site is remote; otherwise water might be hauled or pumped at a lower cost. In almost all, reuse of grey water is critical for landscaping and any other high volume water uses.

• Water use monitoring is very important, and desalinization may be necessary • Rainwater collection can be cost efficient • Waste treatment may be low priority if groundwater is already not potable

Other factors are important for sighting a marine ecolodge12

• Avoid damaging attributes including mangroves, wetlands, dunes, estuaries, historical sites, sacred or culturally significant sites, nesting and habitat sites for marine reptiles, mammals and seabirds.

:

• Site the lodge in a location where minimal coastal terrain will need to be modified. • If facilities must be built on the beach (in front of the dune) consider low investment, non-

permanent buildings. These buildings can be removed before storms and rebuilt afterwards. • Minimize vegetation clearance and maintain tree and dune vegetation cover. • Incorporate areas to maintain a buffer zone or “set back” between the shoreline and facility. • Site piers in water deep enough to accommodate boats rather than relying on dredging. Floating

docking systems may prove to be a more environmentally sensitive alternative to traditional piling construction techniques.

• Site marinas in areas that will maximize the exchange of water through natural flows and tides. • Avoid outward-facing lighting on shoreline, especially in areas where wildlife could be impacted.

12 Halpenny, 45, 48.

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PLANNING AND PROJECT MANAGEMENT

Feasibility Study and Financial/Marketing Plan

A feasibility study is a study of whether a business opportunity is possible, practical, and viable, and how difficult its realization will be. It will consider both the positive and negative impacts of the project and consider financial, logistical, ecological, and cultural factors. In many cases, lodge concessions may be created by a government agency without a thorough determination of these factors relative to the project, and therefore the team considering the project must conduct this activity in-house. A feasibility study should also be conducted when acquiring an existing concession, to determine if the anticipated renovation or upgrading investment has a reasonable return.

A feasibility study will include the following features for an ecolodge13

1. Situation and Competition

:

a. Number, capacity, and location of competition. b. If no competing lodges are in operation, were they operating previously? Why did they

discontinue? Are these reasons still valid? c. Estimate percent utilization of existing lodge capacities. Will the new lodge increase

capacities or pull visitors from existing facilities? d. Level of service, operating costs and technology in competing lodges?

2. Facility Requirements a. Site - Location, zoning, or other restrictions, space of expansion, tax considerations b. Access to transportation– highway and air connections, travel time to regional or national

cities, proximity to other lodges or facilities c. Access to waste and sewage disposal facilities d. Utilities– availability, restrictions or special conditions, rates

3. Buildings and Equipment a. Existing buildings and equipment – cost and difficulty to upgrade or demolish. b. New facilities and equipment – cost and difficulty to build and operate

Planning for a lodge should be foremost considered from the economic perspective, to ensure that the facility can both cover its own expenses and also produce a profit, whether that is a return to private investors, to a local community, or to the park or natural area around the lodge. This plan should also contain a vision statement, so that the idea is both subjectively and pragmatically described in early stages so as to clearly define the project goals, assist in later planning decisions, and to attract funding or industry interest. This marketing plan can contain the following components14

1. Project Description – schematic drawings and plans, infrastructure requirements, land use planning, and proposed phases of project.

:

2. Market Information – tourism assessment of the area, and a definition of how this project intends to complement, expand, or improve existing tourism

13 NXLevel 14 Littlefield, 6-1,6-2.

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3. Strategic Business Plan – a detailed plan describing the existing state of the project, the development strategy, and a schedule.

4. Project Economics – assessment of project costs, projected returns, and how these assumptions were made.

5. Company Profile – senior management, the construction and/or operations team, and any particular information relevant to the group initiating the project.

6. Development Program – details of number of units, operating costs, energy requirements, staff requirements, water needs, waste generation, etc.

Alternatively, the Botswana Tourism Board describes a detailed layout for creating an Ecotourism Business plan as follows15

1. Executive Summary

:

2. Description of the Company (operators, owner) 3. Ecotourism Business Description 4. Ecotourism Market Analysis including Competition Analysis 5. Marketing Study and Visitor Projections 6. Operational Plan 7. Management Structure and Organization 8. Financial Plan and Projections 9. Monitoring and Evaluation 10. Appendices

Master Plan

A master plan is a formal statement of the project’s goals and objectives, including future growth. This is critical for operation of a resort in a remote area where no existing facilities are in place. The master plan will outline the vision and policies of the facility, as well as the practical methods to achieve these. The master plan should include both financial and technical details, as well as scheduling information for incremental construction and development of the area. The establishment of such a plan will not only include the intended expansion of the facility but also include contingencies for possible reductions in visitor numbers. Additionally, this document should include an Environmental Impact Statement and possibly a Social Impact Statement (see relevant sections).

Resort Planning Steps

1. Feasibility/Programming – general review of the proposed facility and existing site conditions, with emphasis on environmental, cultural, and infrastructure assets.

2. Site Analysis – inventory materials on site, topographic survey, identify useable site areas, prepare foundation for further design steps with adequate base mapping and establishment of project goals.

3. Conceptual Design – initial organization and depiction of the development 4. Schematic Design – refinement of concept sketches with scale, dimensions, and definition of site

details, including building arrangements and infrastructure systems.

15 Botswana Tourism Board, 35-39.

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5. Final Design – enhancement of schematic design to level of detail necessary for materials specification and quantities, scheduling, and construction.

6. Master Planning & Documentation – assembly of relevant documents plus Environmental Impact Statement, permits, and financial/business plan into a coherent reference.

7. Construction – will also include revisions to plan documents due to changes, on-site inspections, and writing of operations guides.

The two most critical, and expensive, components of a lodge will be electricity and water. The electrical system is the more costly of the two when a high level of western accoutrement is provided, such as in room outlets, high speed internet, and a wider selection of foods and drinks, which must be frozen or refrigerated. In a PV system this will increase the necessary number of batteries and panels, and with a generator system it will increase the size and noise of the generator, increasing fuel consumption as well as the distance from the clients necessary to keep the area quiet, resulting in higher transmission losses.

The water system can be constructed relatively cheaply in comparison, but hot water requirements will increase expenditure whether for solar hot water panels or for electric geysers. Pumping of water will also drive up costs.

Environmental Impact Assessment

An Environmental Impact Assessment (EIA) is a process by which information about the environmental impacts of a project are collected, both by the developer and from other sources, and taken into account by the relevant decision making body before a decision is given on whether the development should proceed16

EC Directive (85/337/EEC) (as amended) - Article 3

. The EIA can also be a critical tool in deciding where to actually place the lodge (though in practice this is often merely an aesthetic decision).

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1. human beings, fauna and flora,

- The environmental impact assessment shall identify, describe and assess in an appropriate manner, in the light of each individual case and in accordance with the Articles 4 to 11, the direct and indirect effects of a project on the following factors:

2. soil, water, air, climate and the landscape, 3. material assets and cultural heritage, 4. the inter-action between the factors mentioned in the first and second indents.

EC Directive 96/61/EC - Article 218

• ‘pollution’ shall mean the direct or indirect introduction as a result of human activity, of substances, vibrations, heat or noise into the air, water or land which may be harmful to human health or the quality of the environment, result in damage to material property, or impair or interfere with amenities and other legitimate uses of the environment.

- For the purposes of this Directive:

• ‘emission’ shall mean the direct or indirect releases of substances, vibrations, heat or noise from individual or diffuse sources in the installation into the air, water or land.

16 European Commission:Directorate-General XI (Environment, Nuclear Safety and Civil Protection), Glossary. 17 European Commission (EC), 1. 18 EC, 4.

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Several methods are available for conducting an EIA19. The method chosen should be based on the nature of the impact, the availability and quality of data, and the availability of resources to conduct the study20

1. Expert Opinion - means of identifying and assessing indirect and cumulative impacts and impact interactions. Panels can be formed to facilitate exchange of information.

:

2. Consultations and Questionnaires - A means of gathering information about a wide range of actions, including those in the past, present and future which may influence the impacts of a project.

3. Checklists - Provide a systematic way of ensuring that all likely events resulting from a project are considered.

4. Matrices - A more complex form of checklist. Can be used quantitatively and can evaluate impacts to some degree. Can be extended to consider the cumulative impacts of multiple actions on a resource.

5. Spatial Analysis - Uses Geographical Information Systems (GIS) and overlay maps to identify where the cumulative impacts of a number of different actions may occur, and impact iterations. Can also superimpose a project’s effect on selected receptors or resources to establish areas where impacts would be most significant. The ‘Spatial and Network Analysis’ method of ecosystem interactions is appropriate for modern ecolodge development, and contains the following steps21

a. Define the study area for the assessment. :

b. Undertake baseline surveys and consultations. Determine sensitive areas and ecosystem types within the study area.

c. Carryout network analysis for ecosystem types and refine the extent of the sensitive areas.

d. Overlay lodge, road, pathway, and other route options onto the study area and assess impacts of options.

e. Determine the route and lodging option with the least environmental impacts on the sensitive areas

6. Network and Systems Analysis - Based on the concept that there are links and interaction pathways between individual elements of the environment, and that when one element is specifically affected this will also have an effect on those elements which interact with it.

7. Carrying Capacity Analysis - Based on the recognition that thresholds exist in the environment. Projects can be assessed in relation to the carrying capacity or threshold determined, together with additional activities.

8. Modeling - An analytical tool which enables the quantification of cause-and-effect relationships by simulating environmental conditions. This can range from air quality or noise modeling, to use of a model representing a complex natural system.

19 EC, Table 3.1. 20 EC, 20. 21 EC, 46, A2-38.

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Community Involvement

In many lodges which purport to be community based, this local involvement is effectively an afterthought, in that the local community is not engaged until completion of the facility, at which time the local leaders are approached for the purpose of starting a school, hiring staff, or initiating other programs. Because many lodges are located on former traditional lands of these local communities, this approach may reinforce feelings of expropriation among local people. A better technique is to involve the local community from the start, so that they understand the economic, cultural, and conservation benefits of the facility, and can perhaps participate in its planning and development, so that their own interests are not just recognized but optimized. The Botswana Tourism Board describes some actions to take in this regard22

• Meet with the leadership of all communities within 20 km.

:

• Meet with all tribal groups within 40 km of the ecotourism facility and particularly those living in the concession.

• Identify particular community issues (poverty, HIV/AIDS, literacy, etc.) where the operator can contribute to skill and awareness development.

• Identify local labor and skill sets • Identify and discuss with local contractors and suppliers of construction materials, food and

beverage, guide services, etc.

A Social Impact Statement (SIA) can also be generated to evaluate impacts on the community. Although this is not so clearly defined and recognized as the EIA, a formal study can be conducted to define and evaluate the proposed effects of the lodge on the local human population. Questions to include in such research include the following23

• How are individuals within each community affected/involved? Detail number of inhabitants, ethnicity and gender, income type and level, and social and political structures.

:

• Who controls/coordinates at the community level? • What are the benefits the project will bring to the community? Benefits include employment,

income, improved standards of health, education, and nutrition, and improved environmental conditions.

• What are the anticipated distribution and level of benefits and costs? Who will benefit and who will lose from the new facility?

• What are the projected positive and negative impacts on the community as a whole? Changes include resource use patterns, cultural traditions, educational levels, socioeconomic conditions, and political and organizational structures? Are conflicts likely?

• What likely effects will the change in land use patterns caused by the investment have on nutrition and health?

• What changes are desirable?

22 Botswana Tourism Board, 27. 23 Nature Conservancy, 9.

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Project Management

Modern project management techniques are the means by which to control the scope, costs, and schedule for the ecolodge construction and operational opening. A project is a temporary endeavor undertaken to create a unique product, service, or result24 (ecolodge operations, on the other hand, are ongoing ‘processes,’ and do not fit into the definition of a project). By properly defining the scope of the project, managing project resources, and identifying and minimizing risks, the project manager will enjoy a smoother construction experience. With intensive application of project management techniques, these resources will be optimized, resulting in lower construction costs and time. Projects have the following characteristics25

1. A project is carried out only once for an exceptional case.

:

2. A project has a fixed start date and deadline. 3. Every project has a clearly formulated purpose (scope), usually solving a unique problem or the

development of a unique idea.

Furthermore, every project will have these activities26

1. Decisions concerning project results, impacts, and resources.

:

2. Work outputs including construction and systems development. 3. Managing the resources of time, budget, information and project staff, and controlling quality.

The management of these activities is called project management – the application of knowledge, skill, tools and techniques to project activities to meet the project requirements27. Projects are typically divided into ‘phases’ to provide better management control. Phases are usually sequential and are defined by finishing of various technical components, defined by completion and approval of a project ‘deliverable.’ Linear phasing is common to infrastructure projects28

1. Initiating phase – project manager and the client agree on the result and the project plan.

, and this can be divided in the following five phases:

2. Defining phase – a definition of the end result; with a schedule of requirements. 3. Design phase – production of a detailed design. 4. Preparation phase –signed contracts with a contractor or a detailed implementation plan for force

account works. 5. Implementation phase – construction.

After project phasing, a work plan is developed for the project, with more detail concerning phase activities that are to proceed immediately. A Gant chart is a typical work plan layout that details activity durations over time, with specific relationships between activities:

1. Finish-to-Start - FS - Activity B cannot start until Activity A finishes. 2. Start-to-Start - SS - Activity B cannot start until activity A starts. 3. Finish-to-Finish - FF - Activity B cannot finish until activity A finishes.

24 Project Management Institute, 5. 25 Van Rijn, 4. 26 Van Rijn, 4. 27 Project Management Institute, 8. 28 Van Rijn, 6.

20

4. Start-to-Finish - SF - Activity B cannot finish until activity A starts. 5. Lag Time – duration between activities, such as for concrete curing.

An example Gant Chart can be found in the Appendices. Useful software for managing projects and producing visual charts and schedules include MS Project, MS Visio, and Primavera.

Risk management is another important component of project management. The process of risk management seeks to identify and quantify various risks to the project, while also establishing clear reactions to minimize these problems. A risk is the combination of the likelihood that an adverse event will take place and the consequences of the adverse event29

Risk = Likelihood • Consequences

:

Typical risks to an ecolodge construction project include the following: • Cost overruns, especially for cement • Time overruns due to material transport, weather, absenteeism, worker strike, or illness • Unacceptable quality and need to redo work (especially concrete) • Inability to deliver materials due to road conditions (during rainy season) or vehicle size

(especially with long timbers for roof construction) • Weather events include extreme precipitation, prolonged rainy season, flooding, and fire • Health and safety, especially malaria, sleeping sickness, snake bite, and animal encounters • Unavailability of tools or materials in the marketplace at critical times • Lack of water for construction works, especially concrete and masonry • Governmental actions such as changes to concession agreement, import duties, etc.

One way to mitigate material risks is with the use of secure onsite storage (such as a locked 20’ or 40’ shipping container), with materials purchased before they are needed to both ensure availability, reduce delivery delays, and possibly avoid inflation, which can occur rapidly during the African construction season.

Cost estimating is another critical component of project management. In addition to detailed estimates for construction based on a ‘Bill of Quantities’ from the construction drawings, the project manager will also have to estimate the following requirements30

• Site management costs

:

• Offices, sheds, and storage • Access roads • Transport of workers (if off site) • Housing for workers (if on site) • Food, water and sanitation for workers • Health and safety provisions • Insurance and bonds • Tools and electrical service • Vehicle maintenance and fueling

A responsible project manager will establish an accurate project schedule and budget using these standards, with a detailed list of risks and alternative solutions.

29 Van Rijn, 15. 30 Van Rijn, 30.

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PERFORMANCE ASSESSMENT

Typically, there are no established ‘green building’ standards in Africa, though there are some Ecolodge certification schemes, such as the Ecotourism Kenya system or the Botswana Ecotourism Certification System. Additionally, material and fixture availability will be limited if a container of materials is not imported. Still, some amount of evaluation can be conducted in-house or through consultants to either select the best available material for construction or to establish documentation of the selected materials energy/carbon impact. These methods are described below.

Embodied Energy

The Embodied Energy (EE) is the energy required by all of the processes in the production of building materials, including mining and processing of natural resources, manufacturing, transport, and installation (Embodied energy does not include disposal of the building material). Operational Energy is the energy used by the building during use. These concepts can be related, and an increase in embodied energy may or may not result in a decrease in operational energy. In Africa, where raw materials are abundant but processing or manufacturing facilities are distant or non-existent, following the prescriptions for low embodied energy will result in lower purchasing costs, due to the need to import these materials and transport them long distances on inadequate road infrastructure.

The following guidelines are prepared by the Department of the Environment; Water; Heritage and the Arts of Australia31

1. Design for long life and adaptability, using durable low maintenance materials.

for reducing embodied energy in home construction, and they are appropriate to ecolodge projects in Africa:

2. Modify or refurbish instead of demolishing or adding on. 3. Ensure materials from demolition of existing buildings, and construction wastes are reused or

recycled. 4. Use locally sourced materials (including materials salvaged on site) to reduce transport. 5. Select low embodied energy materials (which may include materials with a high recycled

content) preferably based on supplier-specific data. 6. Avoid wasteful material use. 7. Specify standard sizes, don’t use energy intensive materials as fillers. 8. Ensure off-cuts are recycled and avoid redundant structure, etc. Some very energy intensive

finishes, such as paints, often have high wastage levels. 9. Select materials that can be re-used or recycled easily at the end of their lives using existing

recycling systems. 10. Give preference to materials manufactured using renewable energy sources. 11. Use efficient building envelope design and fittings to minimize materials (e.g. an energy efficient

building envelope can downsize or eliminate the need for heaters and coolers, water-efficient taps allow downsizing of water pipes).

12. Ask suppliers for information on their products and share this information.

31 Milne, 138.

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Life Cycle Assessment

Life Cycle Assessment (LCA) is an analytical tool for the environmental impact evaluation of a product or service system through all stages of its life, from resource extraction, processing and delivery (i.e. embodied energy) through service life to final disposal or recycling. In LCA, a fundamental concept is the ‘functional unit,’ where an actual building component unit is specified over a defined time span32. Therefore, instead comparing 1 kg concrete to 1kg fired brick for a wall, for example, LCA would include all the peripheral requirements (plaster, refinishing, different foundation sizing, etc.) as well as any recycling or demolition inputs necessary after the defined period (i.e. 15 years) of the structure. Instead of calculating with mass, this would ordinarily be calculated in a unit of square meters. Life Cycle Costing is a related technique to sum costs associated with an asset, including acquisition, installation, operation, maintenance, refurbishment, and disposal costs33

Useful software for conducting an LCA include GaBi (Germany) and SimaPro (Netherlands), Athena Environmental Impact Estimator (Canada), BEES (U.S.), and Envest 2 (United Kingdom). However, Energy costs for materials are very specific to different geographical regions, and as yet no LCA program has been developed for Africa.

.

Elements of a LCA are as follows34

1. Goal and Scope Definition: The goal and scope for the study are clearly defined.

:

2. Inventory Analysis: Actual collection of data and the calculation procedures, which are analyzed and quantified, and produced as a table.

3. Impact Assessment: The impact assessment translates the inventory analysis into environmental impacts and evaluates their significance. This may require several iterations.

4. Interpretation: In this phase conclusions and recommendations are drawn from the inventory analysis and the impact assessment.

Design for Deconstruction

Design for Deconstruction (DfD) principles are of particular use in remote ecolodges made of ‘permanent materials’, but which are also situated in natural areas and parks. In a DfD approach, the life cycle of the materials is emphasized by using durable materials which can be easily recycled. A simple example of this would be the use of high quality fired bricks or concrete blocks with a lower quality mortar, so that the blocks can be easily cleaned and reused after deconstruction of the building. Primary principles for DfD are as follows35

1. Reuse existing buildings and materials.

:

2. Design for durability and adaptability. 3. Design for deconstruction by using less adhesives and sealant 4. Use less material to realize a design

32 Nebel, 5-6 33 Nebel, 14. 34 AS/NZS ISO 14040-14043 35 EPA Pollution Prevention Program Office, 46.

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Other principles are the following36

1. Maximize clarity and simplicity of the building design.

:

2. Use building materials that are worth recovering. 3. Minimize the number of fasteners used when possible. 4. Simplify connections between parts, to enable easier deconstruction. 5. Separate building layers and systems (i.e. mechanical, electrical). 6. Minimize the number of components (i.e. use fewer larger elements). 7. Use modular building components and assemblies. 8. Disentangle utilities from the within the structure’s walls, ceilings, and floors. 9. Provide easy access to components and assemblies (windows, etc). 10. Make connections between components and parts visible and accessible.

Some possible materials and material combinations suitable to building ecolodges in Africa include the following:

1. Safari tents, i.e. ‘Meru Tents’, on sand foundations with wooden box retaining walls. 2. Stone rubble foundation with 1:3:6 concrete cap (reinforced or unreinforced) 3. 1:4 concrete blocks with 1:6 or 1:8 cement mortar 4. Industrially fired clay bricks with 1:6 or 1:8 cement mortar 5. 1:20 cement stabilized soil blocks with mud mortar 6. Wattle and daub or cob walls 7. Wooden framed walls 8. Unstabilized rammed earth walls or adobe 9. Straw bale walls 10. Thatch roofs

‘Buy Local’

A fundamental component of ecolodges by definition is the stimulation of the local economy, and the possible displacement of resource extraction from the natural area of interest (such as charcoal making, poaching, and illegal fishing) to a more efficient and regulated economy elsewhere. In this regard, an emphasis on local purchase of building materials is essential in fulfilling this go

One could argue that most local technologies are also low-energy and also low-impact, thereby also fulfilling the goals of low embodied energy and Life Cycle Costing. Generally this is true, though there are notable exceptions. Primarily, the local firing of bricks has made a devastating impact on forestation in Africa, and the requirement for large, older trees (for higher fuel content and longer burn times) due to the lack of suitable fuel alternatives (such as coal dust or recycled oil) might outweigh the other benefits. In this case, one can make an argument for the use of cement stabilized soil blocks or rammed earth.

Another problematic local resource is river sand, which is commonly extracted at the end of the rainy season and sold on roadsides throughout Africa. Though this material has almost no embodied energy, destabilization of the river bank can result in accelerated erosion downstream as well as higher turbidity which can affect fish populations. Furthermore, river sand is a poor quality concrete component due to

36 EPA Pollution Prevention Program Office, 48-9.

24

its small, rounded particle shape and high clay and silt content. However, under controlled circumstances it can be an excellent resource.

Therefore, if a ‘Buy Local’ policy is to be emphasized, consideration should be given to the effects of these purchases in sustaining environmentally degrading processes. Possibly, this approach could result in identification of better alternatives (such as an unused and cheap fuel source for firing bricks or a better sand quarry in the area) which could be developed and informally ‘certified’ as more ecological.

Monitoring and Evaluation

In a traditional tourism venture, success of the lodge would be determined by conventional financial measures such as revenues, profit, occupancy, increase in market share, and growth of the business. These factors are all relevant to an ecolodge, but additional measures should be in place to determine the benefits to the location in regard to environmental and social criteria. Some methods to achieve this are described below37

• Set overall goals and indicators for environmental performance and the management of natural and social environments.

:

• Generate baseline data on environmental and social indicators. • Implementation of monitoring system such as Limits of Acceptable Change. • Integration of monitoring results into operations.

Monitoring is the measurement of a set of indicators that are tracked over time, while evaluation is the regular, periodic assessment of progress against a set of reference values38. Monitoring can be defined in a hierarchical cycle39

1. Impact - Long term environmental/social/financial change, the ecolodge vision.

:

2. Outcome (goals) - Medium term change or intermediate success to measure change 3. Output - Immediate results, such as skills and knowledge. 4. Process - Activities undertaken using inputs to produce outputs, with quantifying indicators, such

as frequency. These can include trainings, workshops, and classes, and can be formal or informal.

5. Inputs – Resources including time, money, people. A suggested approach to this process is to first establish the vision of the system, and then define outcomes and outputs. Other tools in the process include reporting, to document processes and indicators at regular intervals, and feedback, whereby the accomplishment or modification of outcomes and outputs can be analyzed. Critical to this is the use of indicators, or measurable states that provide evidence that a certain condition exists or that certain results have or have not been achieved40

The International Ecotourism Society developed four ‘components of sustainability’ to serve as outcomes for a typical ‘sustainable tourism’ program, and these are detailed below, with typical indicators bulleted below each component

.

41

37 Nature Conservancy, Ecolodge Guidelines, 6.

:

38 Toth, 17. 39 Toth, 18. 40 International Social and Environmental Accreditation and Labeling Alliance. 41 Toth, 34, 37.

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1. Minimize environmental damage a. Reduction of solid waste

• Kilograms of waste to landfill or incinerator per sector specific activity • Percentage of total waste that is reused and/or recycled

b. Minimization of contamination through waste discharge • Kilograms of chemicals used per tourist specific activity (guest-night, tourists) • Percentage of biodegradable chemicals used to total chemicals • Solid Waste Disposal

c. Energy Conservation • Total energy consumed per tourist specific activity (guest-night, tourists, etc) • % of total energy from renewable sources • CO2

d. Water Conservation footprint

• Total volume of potable water consumed per tourist specific activity • Sewage is treated effectively

2. Minimize socio-cultural damage a. Codes of behavior

• Appropriate Code of Behavior is integrated into operation b. Contribute to community development

• Percentage of annual gross income contributed to local community • New business and/or staff promoted

c. Stakeholder consultation • Consultation and dialog with community or other local stakeholders

3. Maximize economic benefits for local communities a. Local employment

• Percentage of staff locally hired • Percentage of wages paid to local staff

b. Local purchase of services or goods • Percentage of purchases of services and goods from local or regional providers

4. Operational management and quality a. Integration of sustainability into operation

• Company sustainability policy • Management system for key sustainability issues • Customer service staff uses sustainable practices

b. Maximize customer satisfaction - Average customer satisfaction rating

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CONSTRUCTION AND MATERIALS

Technical skill and construction skill is typically absent in villages, and finding urban people with willingness to work in a remote area for an extended time can be challenging. Furthermore, maintaining systems with high technical requirements can add to operating costs in the long term and will likely result in occasional disruptions to service. These constraints should be considered early in the planning process. From the author’s experience on many remote projects in Africa, many local people hired for major construction projects will be unprepared for the sustained effort required for completion, and this should be included in budgeting/scheduling through planned raises, work hiatus, and team rotation/ replacement. Training locals, who will have a stake in the project’s success, in advanced skills such as PV system operation could be a significant long term cost saving, if it is successful and the individuals remain engaged in the project.

Fundamentally, for most construction projects or facility operations, one simple equation can be used to evaluate many decisions:

1 liter diesel fuel = 1 villager daily wage

From this perspective, many facets of construction and mechanical systems have a direct impact on local employment. Examples include use of power tools versus human labor for sawing and digging, powered compressed earth block equipment versus manual presses, treadle/Afridev pumps vs. electric pumps, delivery of produce by bicycle vs. truck, and use of manual labor for road building vs. heavy equipment. Of course, this approach comes at some detriment to time, capacity, and quality. This is especially true in the mixing of mortar and concrete, where far superior results are to be found using a powered mixer, particularly for pours of over 3m3

Material transport

, or when washing of the sand or aggregate is necessary before making the concrete batch (as this can be quickly performed with a tilting powered mixer.)

Transportation can be another major cost with remote sites; costs of materials can easily double or triple with truck delivery. Importation is also expensive, in that shipping costs from Europe/North America/China as well as import duties can similarly increase costs. If possible materials should be found as close to the construction site as possible and an affordable delivery method established; this may include purchase of a delivery vehicle for the duration of the project.

27

Photo 5 Typical transportation scenario for remote destinations, Nairobi.

Photo 6 Old South African military vehicle typical of lodge construction.

The type of vehicle needed for the project should be analyzed carefully. A larger capacity truck (>5-ton) will reduce transportation unit costs, but it can also have a greater impact on the road access to the site, and trucks with long wheel bases may have difficulty maneuvering in a site that is rocky or forested, due to both turning radius and the overhanging bumpers front and rear and the very low vehicle chassis. In many cases the purchase of a project vehicle is assumed, while a careful financial analysis might suggest otherwise.

Construction impact

Labor and power equipment again are a tradeoff on a construction site. Heavy equipment will produce a much larger physical and auditory impact on the area, whereas people on site will have a larger impact on local water quality and may also produce a significant physical impact. In the case that heavy equipment is to be used, such as a Caterpillar, front end loader, tractor, or grader, work should be organized such that all excavation or earth moving requirements can be performed in one stage. This will also reduce cost, though it will require detailed site plans at an early stage of the construction process; though this is of course desirable, it is not always a given on such projects.

If local labor is used and the workers will reside at the site, several dimensions must be considered: accommodation, water supply, food supply, waste removal, and short and long term physical impact. Additionally, transportation and medical services must be provided. In the best case scenario, future staff housing or mechanical/storage facilities can be erected first, along with a water supply and storage structure (this will also facilitate construction), and large numbers of workers can thus be housed on site, preferably in an area that will not be visible to guests during the multiple rainy seasons that may be required to rehabilitate the landscape.

Season and storm water control

A Storm Water Pollution and Prevention Plan42

42 Developing Your Stormwater Pollution Prevention Plan: A Guide for Construction Sites, EPA

(SWPPP) is the best means by which to minimize disturbance to the site through erosion and sedimentation. Fundamental to this is the minimization of

28

disturbed area, followed by sequential construction planned around the rainy season, and establishment of erosion control measures, including silt fencing, check dams, wattles, and diversion of stormwater around the site. For more information on this approach see the Appendix, and for a thorough description of erosion and sediment control measures, visit the EPA website.

Boundaries can be defined, preferably with some foreign device such as barrier tape, to limit footpath establishment both during and after working hours. Use of water from any surface source, such as a river, stream, or lake should be strictly defined and monitored to reduce impact on this source. Alternatively, staff can be accommodated off site, or even in their home villages, but this will increase transportation costs immensely, as well as impact social factors detrimental to the work environment, such as alcohol consumption, tardiness and absenteeism, or employment duration.

Tools

Tools necessary for a remote project with technical systems can be divided into three types: technical/engineering tools; powered construction tools; and manually operated tools. Further, manually operated tools can be subdivided into skilled tools and unskilled tools. A basic list of these is listed below, while a more complete tool list is included in the appendix.

Technical/engineering tools:

• Laptop + CAD + engineering software • Digital camera • GPS • PV and wind evaluation tools

• Builder’s level or theodolite • Abney level • 100m + 30m + 8m tapes • Measuring wheel

Powered Construction tools:

• Concrete mixer + vibrator • Chainsaw • Welding machine + grinder • Cordless tool set

• Reciprocating + jig + circular saws • SDS-Plus hammer drill • Generator

Skilled manual tools:

• Hand saws • Compressed earth block machine

• Treadle pump • Wrenches +sockets + screwdrivers

Unskilled manual tools:

• Shovels • Machetes • Digging hoes • Metal buckets

• Metal digging bars • Hammer • Wheel barrows

Water and pumping

Ideally, the water supply system for the entire facility should be one of the first components completed, as this will facilitate immediate habitation and construction at the site. However, this will also require early detailed planning as to facility needs and site planning to determine the water source, storage, and primary distribution system. In the case that a borehole is to be utilized, a central location or a location near a hill is ideal to facilitate easy pumping to gravity distribution. With lake, river, or marine water source, a sophisticated system design will be required to make the water suitable for drinking, which is also desirable for construction purposes, especially concrete works.

29

Photo 7 Approtec 'Money Maker' treadle pump is a good choice for construction works.

Photo 8 Typical petrol powered water pump.

Temporary or permanent pumps are options for the construction phase. Temporary pumps include firefighting pumps, petrol or electrically powered centrifugal pumps, or manually operated treadle pumps. Permanent pumps, which would be installed in the completed water system for long term operation at the facility, include submersible pumps and centrifugal pumps. For more information on permanent installations see the mechanical systems section on water.

Generators

Several options exist for mobile power supply, and these options should be considered for construction plus long term use at the facility:

• Diesel generator • Petrol generator • Generator/welder • Moveable/fixed

• Sound attenuated • 240v AC + 12v DC • Single phase • Three phase

Generally, a 4kVa generator is sufficient for most construction works (running concrete mixer, pumping water, minor welding, and powering communications equipment), whereas a long term backup generator for the facility may be of the order of 12-50kVa, or higher in some instances (please see Electricity section for more discussion about generator sizing). Therefore, the generator selected for construction should be specified for future construction and maintenance activities, but not necessarily for lodge backup. In some cases, where wind or PV will provide most of the power for the facility, a smaller unit is feasible, and in this case it should be designated as sound attenuated so that it can function under normal circumstances with minimal intrusion on the guest experience.

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Materials and Techniques

A limited number of materials are available at an affordable price in most African countries, and hardware selection is also low. In particular fabricated steel, aluminum products, stainless steel hardware, and Western style cladding systems are very expensive, if they are available at all. In place of this, one must often use locally produced wood, welded round bar, threaded rod, and lower quality nails and bolts. However, this situation is compatible with the principles advanced for ecolodge construction. Advice on the use of local materials is the outlined below:

Fired Brick

Locally fired brick is one of the most common building materials in Africa today, used on construction in small remote villages, city mansions, and even multi-story concrete framed buildings. Because massive amounts of older growth wood must be used to fire the brick, this product (along with charcoal production) is responsible for significant deforestation throughout the continent. Rwanda has instituted a ban on locally fired brick without permit, but in most countries the practice is so widespread and entrenched that no change in course seems possible. Some donor organizations such as DFID are promoting school construction with compressed earth blocks (see below). Unfortunately, traditional construction techniques such as adobe, rammed earth, and wattle and daub are perceived as inferior, despite the fact that most locally fired bricks have very little advantage in compression strength or durability.

Photo 9 Staff housing of locally fired brick in Majete Wildlife Refuge, Malawi.

Photo 10 Safari tent with brick bathroom, Majete Wildlife Reserve, Malawi.

In the case the bricks are necessary in construction, efforts should be made to minimize the amount of wood necessary. This can be accomplished by replanting trees, using alternative fuels to fire the wood, such as used oil, coal or charcoal dust, or waste agricultural materials such as tobacco stems and rice husks, and reducing the total number of bricks necessary. Producing a more uniform brick will also reduce the amount of mortar necessary for the wall construction.

Wood

Eucalyptus is the most commonly available wood in many locations, but pine and hardwood is also to be found. Wood can typically be purchased as poles or as lumber in common American dimensions such

31

as 2” x 6” and 2” x 8”. Most wood will not be ‘sustainably harvested,’ meaning that it is not replanted. Furthermore, in many locations ‘kiln dried’ lumber is not available: The material is not dimensionally stabile and significant splitting, warping, or twisting may occur during and after construction. To eliminate some of these problems, some projects may import containers of industrially produced wood from other countries (notably Brasil), but this of course increases transport costs and carbon footprint of the material. For high end construction this may be the only alternative to use higher quality finished wood surfaces. Ultimately, a program to replant in kind (or in greater number) nearby harvested trees is the most sensible action to take, as long as these trees are maintained to maturity.

Stone

Local stone can be a huge asset to a remote project, especially if local masons are available to dress the rock to useable dimensions and build walls. Typical stone types include basalt near volcanic areas, laterite and granite in areas where murram soil is common, and limestone blocks quarried from marine deposits along the Indian Ocean. Basalt rock is often very hard and can be difficult to produce an rectilinear units, whereas laterite may be very low in strength and durability. Limestone blocks are often of average strength but can be dressed easily.

Photo 11 High quality, angular basalt in central Ethiopia.

Photo 12 Limestone block quarry, Manda Island Kenya.

Thatch

Thatch is the most common roofing material for the traditional safari lodge. Its procurement is very expensive and time consuming due to the need for huge volumes to construct a high quality roof. The most common thatch material in southern Africa is Hyperthelia dissoluta (called ‘Highveld’ or ‘yellow’ thatching grass in South Africa); Thamnochortus insignis is found on the coast, where it is considered the highest quality material available, and it is even exported43

43 Yates, pg. 13

. Advantages of thatch include its local availability, very low carbon footprint, insulating property, and natural aesthetic. Disadvantages include the costs of roof framing, transportation, and labor, difficulty to put out if on fire, short lifespan (10-20 years), high maintenance, and the relative scarcity of skilled workers to install. Along the Indian Ocean, the most common roof material is ‘makuti,’ which is woven coconut palm fronds, but it is not found very

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far inland and it is not a very durable material compared to traditional thatch, though its cost is much lower.

Photo 13 Thatch roof, Nkhotakota Wildlife Reserve, Malawi. Note the concrete cap for waterproofing.

Photo 14 Makuti thatch roof on Lamu Island, Kenya.

Some tips for thatch roofing:

• Err on the side of ‘over design’ when detailing the roof framing: use maximum pole spacing of 700mm and a minimum pole diameter of 100mm.

• Use 41.5 kg/m2 for design dead load (at 300mm thickness)44

• Minimize valleys in roof design, and keep chimneys or penetrations at the ridge, to eliminate back flashing.

• Eave overhangs should be at least 650mm. • Do not allow rain water to discharge on to thatch from a higher level. • Use Kevlar cord recycled from automobile tires for tying thatch bundles to roof framing. • Minimum roof pitch of 45°, and minimum of 35° over dormer windows • Provide suitable ridge capping, such as reinforced concrete, to prevent water infiltration at this

critical location. • Avoid tall trees that will shade the roof and possibly increase deterioration rate. • Complete thatching before rainy season.

Alternatively, synthetic thatch materials are available that are lighter, more durable, fire resistant, and may even be cheaper than real thatch, thus justifying their procurement in some situations. Technical information on their performance and installation is available from manufacturers, but these materials arguably do not adhere to ecolodge philosophy, and are not covered in this document.

Gravel

Two primary considerations must be made in selecting gravel for use as aggregate in concrete works: strength and size. Strength can be determined empirically, by physically crushing pieces (i.e. with a hammer) and inspecting the local geology (avoid sandstones, while igneous and metamorphic rock are generally okay). Additional tests can be made by mixing concrete samples and crushing in a structural

44 Baden-Powell, pg. 104.

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laboratory, though this is a time consuming process unpalatable to most planners or builders in the early stage of a construction process.

Photo 15 Typical gravel making method with hammers, Malawi.

Photo 16 Screening of sand and gravel is useful to achieve high quality concrete and mortar, northern Ethiopia.

Aggregate size is also important. Because aggregate is often produced manually with hammers, larger pieces are more common and cheaper. This size may be suitable for foundation works or floors (20mm to 50mm), but smaller sizes should be prepared for columns and beams (<25mm). This can either be performed manually as described, or machines can be used, such as the hand operated rock crusher from New Dawn Engineering in Swaziland. Note that gravel purchased from a quarry can be ordered in any desired dimension.

Sand

Sand for construction in Africa is generally of two types: river sand or quarry sand. Quarry sand is better quality due to its rougher texture and absence of clay and silt particles, which severely lower concrete strength. However, good quality river sand can be located, and it also can be sifted, screened, and washed for use in concrete works. In some projects, this may be a very time consuming process, but it must be performed to achieve adequate concrete strengths (i.e. > 20 MPa). Time spent finding a good source of construction sand will result in much higher durability.

34

Photo 17 High quality sand is rough and angular, clean of organics, clay, and silt, and evenly distributed in size.

Photo 18 Exploitation of good river sand deposit for cement block making, Bua River, Malawi.

Soil

Two main soil types are found in Africa: laterite (also called ‘murram’), or montmorrilonite ('black cotton soil'), which is encountered in wetlands and near volcanic areas. Laterites can usually be found just below the surface of vast open plains, grasslands and forest clearings, in regions with heavy rainfall. They are highly weathered soils originating from granite bedrock, formed through break down of rock by chemical decay in tropical conditions; signs of their original structure remain present in the soil. Lateritic clay is generally red in color, and is composed of large quantities of iron oxide and aluminum. It is generally a good soil for compressed earth block construction or for making bricks.

Photo 19 Better quality red laterite soil is often found deeper below the topsoil and above the rock layer, Rwanda.

Photo 20 Low quality black montmorrilonite soil not suitable for construction, northern Rwanda.

Montmorrilonite is expansive clay which is not suitable for earth construction due to excessive shrinkage and swelling characteristics from water exposure. These are found in wet tropical regions, usually close to weathered volcanic rock such as basalt and in low lying swamp areas (due to its very small particle size and electrical charge, it tends to stay in suspension longer than other clays and silts). The name comes from its very dark color, ranging from black and deep grey to dark brown, and from the fact that often cotton is grown on it, especially in India, due to the resiliency of cotton roots to the soil

35

movement during expansion. The soil is extremely clayey with a high plasticity, swells enormously in wet condition and shows equally severe shrinking upon drying. In the dry state the soil is extremely hard. In some locations this is the preferred material for traditional earthen floors.

Topsoil, comprised of organic materials mixed with soil, should never be used for construction purposes.

Lime

Lime is used as a stabilizer in clayey soils, both in road engineering and production of rammed earth walls and compressed earth blocks.

Quicklime is produced in a kiln by firing limestone (CaCO3

CaCO

, calcium carbonate) at around 1000° according to the following reaction:

3 CaO + heat → + CO

Quicklime can be hydrated (combined with water) to produce hydrated lime, which is commonly used in

construction works:

2

CaO + H2O → Ca(OH)

2

Photo 21 Lime blocks with lime mortar construction, Lamu.

Photo 22 Use of lime for compressed earth block stabilization, Rwanda.

Cement

Typically, cement is one of the biggest costs for remote construction projects. Whenever possible, solutions should be found that can minimize cement use, but this can be detrimental to finish quality and durability of the structure. Additionally, many traditional building techniques employ poor construction methods and improper use of cement, and when these are controlled or eliminated, significant savings can be realized. Example of this include concrete floor finishing with cement paste and no sand or aggregate, overuse of water in the concrete mix, foundation concrete without reinforcement, or construction of reinforced concrete with dirty/corroded reinforcement and insufficient concrete ‘clear cover.’ In each case, a smaller cement ratio mixture applied properly will have much better long term results. Before any construction project, the manager should consult a modern concrete text book,

36

establish clear cement mixing rules and procedures, and install quality control procedures including making a breaking test cylinders in a test lab.

Cement is created from limestone in a process similar to that of making lime, but it is heated to approximately 1450°, and additional constituents such as clay, shale, sand, iron ore, bauxite, fly ash and/or blast furnace slag, which may contain calcium oxide, silicon oxide, aluminum oxide, ferric oxide, and magnesium oxide. Gypsum or anhydrite (calcium sulfate) is added to this “clinker”, and the mixture is finely ground to a powder. A partial reaction of this very complex and not completely understood process is outlined here:

CaO + Ca2SiO4 + heat → Ca3O·SiO

Compressed Earth Blocks (CEB’s)

4

Compressed Earth Blocks are compressed with hand-operated mechanical presses or motorized hydraulic machines. They may be stabilized our unstabilized (see below), and they are promoted throughout Africa as a modern application of an ancient building technique. Notable CEB machine manufacturers include Hydraform in South Africa, Makiga Engineering in Nairobi, New Dawn Engineering in Swaziland, and the Auroville Earth Institute in India.

Photo 23 High production Making compressed earth block manufacture from laterite soil Malawi.

Photo 24 Making compressed earth blocks, Bua River, Malawi.

The following procedure can be followed to produce high quality CEB’s:

1. Excavate soil below the topsoil layer. Often, deeper soil is harder to excavate, but it will produce a strong block.

2. Arrange for a laboratory tests on soil to determine properties: gradation and optimum water content. This can be used to compare soils and determine the amount of cement or lime content.

3. Sieve soil to remove all particles >5mm. Crush larger particles and resieve or discard. Add silt or sand if necessary.

4. Add stabilizer and water

• Add lime to soil, thoroughly mix, and allow it to sit for one day. This may allow the lime to break apart clay lumps and create a better mix.

37

• Add cement to soil and immediately hydrate with water and produce blocks. All cement mixtures should be used within 1 hour.

5. The soil block press should be operated as described in the instruction manual; different machines require different soil amounts, operational techniques, and maintenance requirements.

6. Arrange blocks in rows and place under a plastic tarp.

7. Sprinkle water on blocks in morning and evening for seven days, keeping covered. The process is called curing. The longer the blocks are cured, the higher the final strength of the wall will be.

8. After the first seven days, stack blocks up to five rows high and allow further curing for at least one month for lime bricks and seven days for cement bricks. Keep them covered with the plastic tarp when not in use to maintain even moisture content and increase the curing temperature.

Compression – hydraulic vs. manual

There are many different types of block presses. Some are manually operated on some are powered with electricity, petrol, or diesel. Manual presses can be operated by semi-skilled workers, whereas powered machines need more skilled operators and are more expensive to run. Bricks may be square and flat faced, or they may interlock. Interlocking blocks have the advantage of requiring less (or no) mortar between the blocks. Square blocks are more versatile for making curves or intersection walls, as are conventional bricks. Makiga-type machines are the most common manual presses in Malawi, and Hydraform is the most common powered machine.

Photo 25 Hydraform diesel powered hydraulic block press from South Africa.

Photo 26 Makiga human powered mechanical block press from Kenya.

Interlocking vs. flat blocks

Traditional masonry is accomplished with square units, such as bricks, adobe blocks, and chiseled stone. Because Compressed Earth Blocks are molded, they can be shaped to interlock. This has the advantage of minimizing or eliminating the need for mortar, but in practice, manually operated machines do not produce blocks of sufficient uniformity to allow a complete elimination of mortar. Typically hydraulic machines such as Hydraform will enable a mortarless wall section with little difficulty in laying consistent height courses.

38

Photo 27 Using 'confined masonry' technique with flat blocks to achieve better seismic stiffness, Malawi.

Photo 28 Interlocking mortarless Hydraform block construction, Rwanda.

Rammed Earth

Rammed Earth is an ‘in situ’ earth construction technique in which moist soil is packed into a form which moves around the structure to create the walls. As with compressed earth blocks, the soil can be stabilized or unstabilized, and the soil type should be similar. Ramming can be performed by hand, with wooden or steel posts, or mechanical devices can be used, typically powered hydraulically or with compressed air. Mechanized ramming is preferable due to consistency of results and greater compaction energy than can be accomplished manually. Rammed earth is arguably stronger than compressed earth block construction, as there are no mortar joints, but cold joints will exist between layers and mold locations. If these can be quality controlled, a superior wall will result.

Photo 29 Traditional rammed earth house in central Malawi.

Photo 30 Rammed earth house detail, Malawi.

Stabilization means modifying a soil to achieve improvements such as compressive strength, impermeability, strength when saturated with water, or resistance to erosion. Stabilization can be achieved mechanically through compaction, physically through controlling grain size and distribution, and chemically through the addition of materials such as lime or cement.

39

Generally, cement binds better with sand and lime binds better with clay; depending on the ratios of sand and clay in the mixture and the compression strength desired, the amount of cement and/or lime should be adjusted accordingly. This will best be determined by making test blocks before construction that can be tested for strength and water resistance. With soils of less than 30% clay, cement should be used as the stabilizer. The quantity should be between 3% and 10% by weight, although higher cement ratios will always produce higher compressive strength. Cement should be added immediately before block making.

If clays in the soil are greater than approximately 50%, lime should be used for stabilization. The quantity should be between 6% and 15% by weight, although at some point the percentage of lime is optimized, beyond which the compressive strength will decrease. Some literature suggests that lime should be added a day before block making to allow the lime to break up soil lumps and increase compaction.

Photo 31 Use of a Hydraform soil mixer for thorough cement and soil mixing, Ethiopia.

Photo 32 Experimentation with a soil stabilization product for road construction, Rwanda.

40

WATER SUPPLY AND PURIFICATION

Water supply is one of the most critical components of an ecolodge, and its provision can be a major cost from the engineering perspective, in initial cost and operation / maintenance. Most water sources will require some form of purification, although in the tourism industry one must also concede to visitor preferences for bottled water due to its perceived safety. Water is not really ‘consumed,’ as with other resources like fuel, food, or electricity, and so water should be thought of in its total stream from source to purification, though use, to wastewater treatment, and then to its ultimate return to the local ecosystem, whether by direct discharge, subsurface flow, or for landscaping.

Water purification is any process which removes particle or organic loads from the water. Called ‘water treatment’ for drinking water, this can require one or more stages, including pre-treatment, coagulation/flocculation, sedimentation, filtration, and disinfection, depending on the source. Typically, a remote lodge treatment system will be used only for improving water clarity and odor, as all drinking water will come from bottles (at least for guests; further treatment may still be required for staff use), but many water sources can be cost-effectively treated for safe consumption. These processes will require both physical improvement of the water and disinfection to eliminate microorganisms. These processes are related, in that more effective physical or chemical processes removing sediment and improving water clarity will result in more efficient disinfection.

These are the primary factors in selecting a water treatment process45

1. Treated water specifications

:

2. Quality of the raw water, throughout the year 3. Locally available materials, equipment, maintenance, and power source 4. Costs of competing treatment processes

Water treatment system design should consider the following factors to reduce cost, complexity, and difficulty of repair in remote environments in Africa46

• Mechanical equipment reliance should be minimized or be comprised of what is available locally.

:

• Gravity powered devices for mixing, flocculation, filtering, and distribution should be favored over mechanical equipment.

• Head loss should be minimized whenever possible. • Mechanization and automation are appropriate where operations are hard to perform manually, or

where reliability is greatly improved. • Indigenous materials and manufacture should be chosen over imported and premanufactured

components where possible. • Reduce design life of the system to 5-10 years to allow for advances in technology and equipment. • Design should be according to the water available on site; specific treatment objectives should be

established before buying or designing a system. • An operation plan must be part of the system design and installation package.

45 Schulz, pg. 18. 46 Schulz, pg. 10.

41

Reductions of bacteria, viruses and protozoa achieved by water treatment processes1

Treatment process Pathogen Removal amount possible Pretreatment

Roughing filters Bacteria Viruses

Protozoa

50-95% if protected from turbidity spikes No data available No data available

Microstraining all Generally ineffective Off-stream/bankside all 0-90% removal (in 10–100 days), avoiding intake @ periods of peak turbidity Bankside infiltration all 99.9% after 2m

Coagulation/flocculation/ sedimentation

Conventional Clarification (depending on the clarification coagulant, pH, temperature,

alkalinity, turbidity)

Bacteria Viruses

Protozoa

30-90% 30-70% 30-90%

Lime softening

Bacteria

Viruses

Protozoa

20% @ pH 9.5 ( 6h @ 2–8°C), 99% @ pH 11.5 ( 6h @ 2–8°C) 90% @ pH < 11 ( 6h), 99.99% @ pH > 11, depending on the virus and on

settling time Low inactivation 99% through precipitative sedimentation and inactivation @

pH 11.5 Ion exchange All 0% Filtration

Rapid sand filtration Bacteria and

Viruses Protozoa

? to 99% under optimum coagulation conditions ? to 99% under optimum coagulation conditions ? to 99% under optimum coagulation conditions

Rapid sand filtration (under optimum filtration ripening,

cleaning and refilling and in the absence of short circuiting)

Bacteria and Viruses

Protozoa

50- 99.5% 20- 99.5% 50- 99.5%

Microfiltration membrane (providing adequate pretreatment

and membrane integrity conserved)

Bacteria Viruses

Protozoa

99.9–99.99%, <90%

99.9–99.99%,

Ultrafiltration membrane, nanofiltration

and reverse osmosis (providing adequate pretreatment and

membrane integrity conserved)

Bacteria Viruses

Protozoa

100% 100% with nanofilters, with reverse osmosis, and @ lower pore sizes of

ultrafilters 100%

Disinfection

Chlorine

Bacteria

Viruses

Protozoa

Ct99: 0.08mg·min/liter @ 1–2°C, pH 7; 3.3mg·min/liter @ 1–2°C, pH 8.5 Ct99: 12mg·min/liter @ 0–5°C; 8mg·min/liter @ 10 °C; both @ pH 7–7.5

Giardia - Ct99: 230mg·min/liter @ 0.5 °C; 100mg·min/liter @ 10 °C; 41mg·min/liter @ 25 °C; all @ pH 7–7.5

Cryptosporidium - not killed

Monochloramine

Bacteria

Viruses

Protozoa

Ct99: 94mg·min/liter @ 1–2°C, pH 7; 278mg·min/liter @ 1–2°C, pH 8.5 Ct99: 1240mg·min/liter @ 1 °C; 430mg·min/liter @ 15 °C; both @ pH 6–9

Giardia - Ct99: 2550mg·min/liter @ 1 °C; 1000mg·min/liter @ 15 °C; both @ pH 6–9

Cryptosporidium - not inactivated

Chlorine dioxide

Bacteria

Viruses

Protozoa

Ct99: 0.13mg·min/liter @ 1–2°C, pH 7; 0.19mg·min/liter @ 1–2°C, pH 8.5 Ct99: 8.4mg·min/liter @ 1 °C; 2.8mg·min/liter @ 15 °C; both @ pH 6–9

Giardia - Ct99: 42mg·min/liter @ 1 °C; 15mg·min/liter @ 10 °C; 7.3mg·min/liter @ 25 °C; all @ pH 6–9

Cryptosporidium - Ct99: 40mg·min/liter @ 22 °C, pH 8

Ozone Bacteria Viruses

Protozoa

Ct99: 0.02mg·min/liter @ 5 °C, pH 6–7 Ct99: 0.9mg·min/liter @ 1 °C, 0.3mg·min/liter @ 15 °C

Giardia - Ct99: 1.9mg·min/liter @ 1 °C; 0.63mg·min/liter @ 15 °C, pH 6–9 Cryptosporidium - Ct99: 40mg·min/liter @ 1 °C; 4.4mg·min/liter @ 22 °C

UV irradiation Bacteria Viruses

Protozoa

99% inactivation: 7mJ/cm2 99% inactivation: 59mJ/cm2

Giardia - 99% inactivation: 5mJ/cm2 Cryptosporidium - 99.9% inactivation: 10mJ/cm2

42

Objectives of water treatment

Any drinking water should have the following qualities47

• Free of pathogens

:

• Low in concentrations of toxic or harmful chemicals or minerals • Clear • Not saline • Free of offensive taste or odor • Non-corrosive and non-scaling

The following tables give a summary of basic research on pathogenic organisms, but note that more specific information may be available in the country in which the lodge is located. Pathogen occurrence and quantity depends on the physical and chemical characteristics of the catchment area as well as the intensity and range of human and animal activities48

The following terms are used to describe water quality

. These can be point sources, such as a village or farm, or non-point sources, such as dispersed settlement, grazing animals, and wildlife. To ensure accuracy with test results, water source testing should be done onsite at numerous occasions throughout the year, including after significant events such as flooding.

49

• Turbidity - organic or inorganic material in water which causes a cloudy appearance by the scattering and absorption of light. Turbidity can be caused by very fine particles such as clay which do not settle in a short period of time and must be removed by flocculation.

:

• Taste is a moderately accurate sense and people are able to detect concentrations from a few tenths to several hundred parts per million (ppm).

• Color is a primarily aesthetic concern caused by organic material or some metal ions. • Odor is a very sensitive human sense, capable of detecting low concentrations down to parts per

billion (ppb). This is primarily an aesthetic concern. • pH is a measure of the negative logarithm (log) of the hydrogen ion concentration in water, and it

has an effect on coagulation, chlorination, and water softening, as well as the scaling-potential. pH less than 7.0 is acidic; pH more than 7.0 is basic.

• Total Solids (TS) is the sum of Total Dissolved Solids (TDS) and Total Suspended Solids (TSS). • Conductivity/Resistivity can provide an assessment of total ionic concentration, because pure

water contains few ions and has a high resistance to electrical current, • Bacterial contamination is quantified as “Colony Forming Units” (CFU, a measure of the total viable

bacterial population), found by incubating a sample on a nutritional medium and counting the number of bacterial colonies that grow.

• Pyrogens are substances that can induce fever in warm-blooded animals; they include endotoxins which are cell walls from living cells or fragments from ruptured cells.

• Total Organic Carbon (TOC) is a measure of the organic, oxidizable, carbon-based material in water.

47 Schulz, pg. 12. 48 WHO Guidelines for Drinking-water Quality, pg. 136. 49 Pure Water Handbook, pg. 16.

43

• Biochemical Oxygen Demand (BOD, specified in mg/L) is a measure of organic material contamination in water, described by the amount of dissolved oxygen required for the biochemical decomposition of organic compounds and the oxidation of certain inorganic materials over a five-day period.

• Chemical Oxygen Demand (COD, specified in mg/L) is measure of organic material contamination in water, measured by the amount of dissolved oxygen required to cause chemical oxidation of the organic material in water.

• Water Hardness is a description of the presence of calcium (Ca2+) and magnesium (Mg2+

• Iron can change from the water-soluble ferrous state (Fe

) ions, which can cause scale formation at levels of 5 to 8 mg/L. ‘Carbonate hardness’ typically is found in dolomitic limestone (calcium and magnesium carbonate) while ‘non-carbonate hardness’ generally comes from chloride and sulfate salts.

2+) to the insoluble ferric state (Fe3+

• Manganese is similar to iron but in much lower concentrations but it is not as common.

), and in the presence of oxygen or an oxidizing agent, can becomes ferric oxide, which is insoluble and precipitates, giving the water a rusty (red-brown) appearance and negatively affecting piping hardware and pumps; some organisms (such as Crenothrix, Sphaerotilus and Gallionella) use iron as an energy source and can form slime that blocks piping. This often occurs when water is pumped from underground to a storage ves sel open to air. Iron also has a distinctive taste.

• Sulfate (SO42-

• Chloride (Cl-) salts are common, and at high levels causes a salty taste and can interfere with water treatment methods and corrode metal parts in water supply systems.

) is common and associated with a bitter taste and laxative effect, and can precipitate at low concentrations.

• Alkalinity includes carbonates (CO3 2-), bicarbonates (HCO3-) and hydroxides (OH-

• Nitrate (NO

), which can contribute to scaling and raise pH.

3-) and nitrite (NO2

-

• Chlorine is usually monitored as free chlorine (Cl

) salts may occur naturally, but their presence usually indicates human pollution, including animal wastes, human sewage, industrial chemicals, and fertilizers. Low nitrate levels are toxic to humans, especially infants.

2) in concentrations of 0.1 to 2.0 ppm. In solution, chlorine gas dissolves and reacts with water to form hypochlorite anion (ClO-

• Chloramines (such as monochloramine, NH

) and hypochlorous acid (HClO). Chlorine may have a disagreeable taste and odor, and can form carcinogenic TriHalogenated Methane compounds (THM’s).

2

• Chlorine dioxide (stabilized sodium chlorite solution) has an extended residual period in distribution systems and does not form trihalomethanes (THM’s). The reaction byproducts chlorate and chlorite ions are possibly toxic.

Cl) are not as effective a disinfectant as chlorine, but provide longer-lasting residuals.

• Silica (SiO2) is very common and occurs naturally from a few ppm to more than 200 ppm. It may cause scaling or “glassing” in boilers, stills, and cooling water systems, or deposits on turbine blades, and it is very difficult to remove.

• Aluminum (Al3+) may be a residual from use of Aluminum Sulfate [Al2(SO4)3, also called ‘alum’], as a flocculant. It may cause health problems.

44

• Sodium (Na+) is natural from salts such as sodium chloride (NaCl), sodium carbonate (Na2CO3), sodium nitrate (NaNO3) and sodium sulfate (Na2SO4

• Potassium is often found with chloride (KCl) and is similar but less common than Sodium Chloride.

). It is also added during water softening, and it is rarely a problem.

• Phosphates (PO43-

• Dissolved Carbon Dioxide (CO

) are common due to runoff of fertilizers and detergents in which ‘phosphates’ are ingredients. They may foster algae growth in surface waters or open storage tanks.

2) combines with water molecules to form carbonic acid (H2CO3

• Dissolved oxygen (0

), and can reduce pH and contribute to corrosion in water lines. Typically of natural origin where water has dissolved rock formations.

2

• Hydrogen Sulfide (H) can corrode water lines.

2

• Radon is water-soluble gas produced by the decay of radium and its isotopes, and it occurs naturally in groundwater from contact with granite formations, phosphate and uranium deposits. It may cause health problems including cancer.

S) is found primarily in well water supplies or other anaerobic sources and can contribute to corrosion. It can be oxidized by chlorine or ozone to eliminate sulfur.

• Heavy metals such as lead, arsenic, cadmium, selenium and chromium can be harmful. • Tannins, humic acids and fulvic acids are common. They cause color and detract from water

aesthetics but have no known health consequences unless they react with certain halogens. • Synthetic Organic Compounds (SOC’s) form a wide variety of potential health hazards. They are

of industrial and agricultural chemical origin, are not readily biodegradable, and can leach from soil or be carried by runoff into water sources.

50 WHO Guidelines for Drinking-water Quality, pg. 137.

Concentrations per liter50

Pathogen or indicator

group

Lakes and reservoirs

Impacted rivers and streams

Wilderness rivers and streams

Groundwater

Campylobacteria 20–500 90–2500 0–1100 0–10 Salmonella — 3–1000 1–4 —

E. coli 10000–1000000 30000–1000000 6000–30000 0–1000 Viruses 1–10 30–60 0–3 0–2

Cryptosporidium 4–290 2–480 2–240 0–1 Giardia 2–30 1–470 1–2 0–1

45

Water testing

Water testing should be performed when selecting a water source, when any change in that source occurs, or when any problem is suspected. Water testing should be performed at the worst time of the year, i.e. during the rainy season for surface water sources, or during the dry season for subsurface sources.

Water sources

No absolutely pure water exists in nature, due to its contact with soil, rock, microorganisms, and chemicals51

. Water can have physical characteristics including turbidity, color, odor, taste, and temperature, as well as chemical characteristics of acidity/alkalinity, hardness, and corrosiveness. Additionally, water can contain organisms such as bacteria, viruses and parasites.

A borehole is a very common water source for ecolodges in Africa. This is due to the reliability and purity of the water source, and the relative lack of maintenance on the system. Some lodges may have two or more boreholes to provide water for landscaping, pools, and game ponds as well as visitor, kitchen, and staff use. Borehole drilling is typically done by technicians with little formal training and no hydrological data to dictate location, spacing, quality, or other parameters. As a result, yield and quality may not be optimum for a chosen location. Additionally, many boreholes are established without any management at the macro level, meaning there is no oversight of total water extraction, diminishing yields or lowering water tables, or any other water quality considerations.

51 Water Purification, Distribution, and Sewage Disposal, pgs 14-15.

TREATMENT SYSTEM MATRIX

Source Pretreatment Sedimentation Coagulation Filtration Disinfection Other Borehole none none none none chlorine may

be desired minerals removal

Stream diverter, strainer rainy season rainy season sand or cartridge

UV, chlorine, ozone

combine with microhydro

River strainer + foot valve grit chamber yes sand or

cartridge UV, chlorine,

ozone

Lake settling vessel yes in line or vessel sand or cartridge

UV, chlorine, ozone

Rainwater first flush device storage tank none sand or cartridge

UV, chlorine, ozone

Ocean settling vessel none none ultrafiltration RO for desalination

Pool - none none rapid sand + cartridge chlorine

46

Photo 33 Mobile borehole drilling rig, Manda Island Kenya.

Photo 34 Fresh water ‘lens’ above salt water layer in shallow well, Lamu Island, Kenya.

Rivers and streams, or surface flow waters, are less attractive than subsurface flows due to greater variability in quantity and quality. Particularly in Africa where intensive farming is practiced without terracing, rainy season results in tremendous sediment loads in rivers. This may not be problematic in national parks or mountainous areas however. Typically, streams have better water quality than rivers and will require less treatment before use, but with a higher energy they will transport more sediment which must be removed before it encounters fittings or mechanical equipment.

Photo 35 Water collection box with gravity distribution on Nchisi Mountain, Malawi.

Photo 36 Water intake pumps on Lake Malawi.

Lake water quality varies tremendously. Lake Victoria, which is heavily populated and has problems with invasive plants and massive fertilizer runoff, is of much lower quality than Lake Kivu between Rwanda and DRC, where both population and the level of industrial agriculture practice are lower. As a result, the water treatment scheme for Lake Victoria will be much more complex and costly, and the final product may not have the desired clarity or lack of odor.

Rainwater harvesting is a relatively uncommon technique due to the high cost of the system (if plastic tanks are used) and the relatively low quantity that can be stored. This technique can be improved if multiple roofs are linked, if surface runoff water is collected, and if voluminous (>20000 liter) underground storage is employed. In this case, rainwater harvesting is a viable solution for landscaping,

47

washing, and other non-potable requirements, especially in areas where water is more difficult or expensive to purify, such as ocean lodges. Rainwater availability is seasonal in most of eastern and southern Africa. In locations with a longer rainy season and where fresh water costs are high, rainwater collection is viable for an ecolodge.

Photo 37 Rain water collection system on Manda Island, Kenya. Storage tank is shown in foreground.

Photo 38 Typical rainwater collection system from metal roof, Mbita, Kenya.

Pretreatment

Pretreatment includes coarse processes such as screening, sedimentation, rough filtration, and storage. The purpose of pretreatment is to make later processes more efficient, faster, cheaper, or more thorough. Reducing turbidity is a major component of pretreatment in river/stream/lake source water systems.

Sedimentation and Coagulation/Flocculation

Sedimentation is any method using the settling of suspended particles, including microbes, to remove them from the water, though sedimentation typically applies to larger particles which are settled without a chemical flocculent. Coagulation uses a natural or chemical coagulant agglomerate suspended particles (including microbes) into ‘flocs’, and enhance their sedimentation in a water vessel. Often this process is accomplished with two vessels in series, as well as a third vessel, where drinking water will be stored at least 2 days to reduce microbes52

.

52 WHO Guidelines for Drinking-water Quality, pg. 141c.

48

Filtration

Filtration is any physical process of removing water impurities, but often filtration has chemical or biological components53.

FILTRATION SPECIFICATIONS

TECHNIQUE MWCO -

molecular weight cut-off (Da)

Microfiltration >105

Ultrafiltration 103-105 Nanofiltration 102-104

Reverse osmosis 102

Groups of pathogenic micro-organisms54

Family Known germs Size range (microns)

Bacteria E-coli (Escherichia coli), Salmonella (Salmonella typhimurium), Cholera (Vibrio cholerae) 0.2 - 5

Viruses Hepatitis A, Norwalk Virus, Rotavirus, Poliovirus ~0.02 - 0.2

Protozoans Amoeobiasis (Entamoeba histolytica), Giardia lamblia (Giardia intestinalis), Cryptosporidium (Cryptosporidumparvum) 1 - 15

A sand filter retains microbes through physical and chemical processes, including physical straining, sedimentation and adsorption.

Slow sand filters develop biologically active layers of microbes (called the schmutzdecke), which acts to destroy or inactivate pathogens.

Membrane, porous ceramic or composite filters are filters with defined pore sizes and include carbon block filters, porous ceramics containing colloidal silver, reactive membranes, and polymeric membranes. These devices act by physical separation of microbes and other particles from the water molecules. Some filters also employ chemical antimicrobial or bacteriostatic surfaces or other chemical modifications to destroy or inactivate microbes55

Cartridge filters of cotton, cellulose and synthetic yarns, chopped fibers bound by adhesives, or “blown” microfibers of polymers such as polypropylene, are disposable units available in the particle-removal size range 0.5 to 100 microns. The water flows through the thick wall of the filter and particles are trapped throughout the complex openings in the medium. Pleated cartridge filters are usually preceded by a depth cartridge filter, and they are flat sheet media surface filters, either membranes or nonwoven fabric materials, which trap particles in the 0.1- to 1.0-micron range (some models work in the ultrafiltration range of 0.005- to 0.15-micron); particles greater than one micron can quickly clog the filter, and it must be replaced. Ultrafiltration cartridges are spiral-wound to allow crossflow operation, which

.

53 Lenntech Water Treatment & Purification Holding B.V. 54 Katadyn WATER GUIDE FOR SAFE DRINKING WATER 55 WHO Guidelines for Drinking-water Quality, pg. 141b.

49

keeps the surface clean by rinsing away solids. They are used to remove colloids, pyrogens, and other compounds for ultrapure water56

.

Photo 39 typical cartridge filter before UV light disinfection, Cape MacClear, Lake Malawi.

Photo 40 Multi stage cartridge filter, Kenya.

Disinfection

Ultraviolet Light (UV) inactivates microbes with low-pressure mercury arc lamps producing monochromatic UV-C radiation at a germicidal wavelength between 240 - 280 nanometers (nm) with a peak wavelength at 265 nm. At this wavelength, the nuclei of the cells are modified, due to photolytic processes, and cell division and reproduction is prevented. The UV dose is the product of UV intensity (expressed as energy per unit surface area) and residence time57

:

Photo 41 UV system after filter cartridge (see photo above) on lake water extraction system, Cape MacClear, Lake Malawi.

Photo 42 Chlorination plant on lake water treatment system, Lake Malawi.

56 Pure Water Handbook, pgs. 37-41. 57 Lenntech Water treatment & purification Holding B.V.

50

UV DOSE = I • T (mJ/cm2

)

DOSE REQUIREMENTS

Species Dose

(mJ/cm2) Legionella Pneumophill 2.04

Streptococcus feacalis 4.5 Clostridium tetani 4.9

E.coli 5.4 Pseudonomas aeruginosa 5.5 Saccharomyces cervisiae 6.0

Hepatitis A virus 11.0 Bacillus subtilis (spore) 12.0

Hepatitis Poliovirus 12.0 Infectious pancreatic necrosis 60.0

UV systems have the following advantages58

• does not alter taste, odor, color or pH

:

• does not require additional chemicals • does not impart toxic by-products into the water • compact and easy to install, very little maintenance • low running costs

and disadvantages:

• does not have residue to disinfect distribution system or storage. • does not function properly if water is turbid (i.e. may not perform in rainy season)

58 Lenntech Water treatment & purification Holding B.V.

E.COLE REDUCTION EFFICIENCY

Dose (mJ/cm2)

Reduction in live microorganisms

5.4 90.0% 10.8 99.0% 16.2 99.9% 21.6 99.99% 27.0 99.999%

51

Chlorination is the addition of free chlorine (hypochlorous acid), di- and tri-chlorocyanurates of free chlorine, chloramines, chlorine dioxide or other chlorine oxidants, including chlorine bleach. Chlorine has the additional benefit of residual chemical action that acts to disinfect distribution lines as well as secondary storage vessels59

Photo 43 Water Missions International cartridge for pool chlorine tablet.

.

Photo 44 Water Missions International rapid sand and chlorination unit using off the shelf pool filters.

Ozonization is another sophisticated process that has recently become economical at the smaller scale. Ozone generators create ozone artificially by means of extremely high voltages using the coronal discharge process, or with UV-light. As a strong oxidant (the extra oxygen in the ozone molecule quickly binds to other molecules), it can be used to oxidize microorganisms such as viruses, bacteria, and protozoa60

2O

. Ozone, consisting of three negatively charged oxygen atoms, is very unstable and it quickly returns to its original form (half-life is approximately 30 minutes in water), according to the following reaction:

3 → 3O

Desalinization

2

Reverse osmosis is the primary method of water purification for desalination. It uses the principle of crossflow membrane filtration, wherein pressurized feed water flows across the membrane, and a portion of this feed permeates the membrane (‘permeate’). The remainder flows parallel to the surface of the membrane to exit the system without being filtered (‘concentrate’), but it also carries off the concentrated contaminants which did not permeate the membrane61

59 WHO Guidelines for Drinking-water Quality, pg. 141a.

.

60 Lenntech Water treatment & purification Holding B.V. 61 Pure Water Handbook, pg. 53.

52

Photo 45 Installed water desalination unit on Manda Island, Kenya.

Photo 46 GE desalination unit at Davis & Shirtliff, LTD, Mombasa.

Key issues for a desalination system include62

• The role of the desalinated water in an overall plan of reduced use, greywater reclamation, wastewater quantities and decomposition, and effluent discharge.

:

• Ecological impacts of impingement and entrainment associated with seawater intake. • Ecological impacts associated with brine discharge. • Siting of the desalination system related to habitat, access, energy requirements, and water

distribution. • Energy production, consumption, and costs. • Regulatory requirements. • Secondary and cumulative impacts.

62 California Desalination Planning Handbook, pg. 7.

53

Reverse osmosis for desalination is more effective and efficient if pretreatment is performed. The following table outlines pretreatment requirements:

Reverse Osmosis Pretreatment63

Fouling Cause Appropriate Pre-treatment Biological Bacteria, microorganisms, viruses, protozoan Chlorination

Particle Sand, clay (turbidity, suspended solids) Filtration

Colloidal Organic and inorganic complexes, colloidal particles, micro-algae

Coagulation + Filtration or Flocculation / sedimentation

Organic Natural Organic Matter (NOM) : humic and fulvic acids, biopolymers

Coagulation + Filtration + Activated carbon adsorption or Coagulation+ Ultrafiltration

Mineral Calcium, Magnesium, Barium, or Strontium sulfates and carbonates

Antiscalant dosing or Acidification

Oxidant Chlorine, Ozone, KMnO4 Oxidant scavenger dosing: Sodium (meta) bisulfate

or Granulated Activated Carbon

63 Lenntech Water treatment & purification Holding B.V.

54

WASTE WATER TREATMENT

Waste water is often a neglected component of public or private infrastructure due to perceived lack of importance or an ‘out of sight, out of mind’ mentality. This is particularly true in Africa, where many large cities have only partial sewerage systems coverage and many wealthy houses still use older techniques such as sewage systems and soakaways, and poorer homes resort to pit latrines. An ecolodge can in this way be both an example and a teaching tool for better techniques and concepts to water management.

Photo 47 Rotating disc filter at hotel on on Lake Kivu, Rwanda.

Photo 48 HDPE septic tank, Nairobi.

Different lodge environments will have vastly different design criteria, including waste quantities and types generated, soil type and percolation rates, water availability, and power and operational resources. As there are many ways to approach the wastewater problem, a good understanding of the options available is a prerequisite for a good design. Likewise, a good design is necessary to run a water/wastewater system that works and which is not detrimental to local flora and fauna.

Conventional sewage treatment typically involves either two or three stages:

1. Primary treatment is the main physical /mechanical component of the treatment process. It involves removing, settling, and skimming the larger components of the wastewater, namely floating and suspended solids in a coarse and fine screen, settling sand and grit in a sedimentation bed, and holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. Primary treatment should accomplish the following64

o Grit / sand removal :

o 60-80% suspended solids removal o 50-60% BOD5

o Up to 80% fats / oils / grease removal removal.

2. Secondary treatment removes dissolved and suspended biological matter, usually by water-borne micro-organisms in a controlled environment. This may require an additional separation process to remove the micro-organisms from the treated water prior to discharge. Secondary treatment is a

64 Parten, 87

55

more sophisticated process, and these biological processes serve to break down the wastewater effluent, resulting in BOD5 and Total Suspended Solids reduction, nitrogen reduction, and disinfection. The following processes are types of secondary treatment65

o Unsaturated biofiltration, where aerobic conditions are maintained within the filter or by having a cycle of saturation and draining:

:

o Saturated biofiltration – anaerobic conditions in up flow filters or subsurface flow wetlands. o Single pass biofiltration – slow sand filter o Recirculating – trickling filter o Attached growth – a slime coat of bacteria is cultured on a synthetic or natural medium o Partially submerged – rotating disk filter o Aerated – plastic pellets inside an aerated effluent chamber

3. Tertiary treatment, sometimes called ‘polishing,’ is anything additional to primary and secondary treatment. Effluent can be further disinfected chemically or physically with UV light, chlorine, ozonation, or further treatment in a lagoon, constructed wetland, leach field, or mechanical filter such as reverse osmosis.

Several concepts must be considered in planning a wastewater treatment system66

• Ability of the system to treat wastes and release water without damage to surface or ground waters.

:

• Local climate and seasonal conditions, including temperatures and rainy seasons. • Initial design, material, and installation costs. • Land area required. • Energy, maintenance, and degree of technical skill required to operate and maintain the system. • Sludge produced in the system, interval of sludge remove, and means to process sludge. • Pump and equipment replacement intervals and costs, and system service life. • System’s reaction to ‘down time’ when little or no waste is being processed (detrimental to

biological systems)

Technical information about the wastewater is required for engineering design of a complex system67

• Daily wastewater production: guests, kitchen, & staff.

:

• BOD – Biological Oxygen Demand • COD – Chemical Oxygen Demand • TSS – Total Suspended Solids • Nitrogen including ammonia, nitrite, nitrate • Phosphorous • Turbidity • Alkalinity • Pathogens

65 Parten, 137 66 Parten, 10 67 Parten, 12

56

A useful design approach developed by the US EPA (Environmental Protection Agency) is the Limiting Design Parameter (LDP). This technique identifies the constituent of the waste water that will require the most land area to effectively process, as well as the type or level of treatment necessary for that soil type68

As any onsite wastewater system will disperse water finally into a soil strata, that soil type must be investigated to determine how it will interact with the pretreatment system

. In a high clay environment where soil percolation rates are low, the total flow of the system would determine the land area required for dispersal. In a very sandy soil with little organic material, wastewater will travel too quickly through the soil to achieve decent biological treatment (though mechanical filtration would work fine on Total Suspended Solids, for example), and nitrogen components of the wastewater, which require biological decomposition, would have to be performed before dispersal.

69

• Hydraulic residence time/infiltrative capacity and rate in the soil strata of interest

:

• Particle size and surface area • Organic content • Physical conditions such as underground channels or bedrock layers

See the section on percolation testing for more information on procedures for testing soil infiltration.

Several options are available for the conveyance of wastewater70

• Gravity system to individual or centralized septic tank(s)

:

• Septic tank effluent gravity (STEG) collection system – gravity flow to an individual septic tank, where settlable solids, greases, and oil removal, then effluent is conveyed by gravity to a centralized treatment location with 80 – 100mm Schedule 40 PVC piping at a burial depth necessary to achieve gravity flow.

• Septic tank effluent pumped (STEP) system – similar to a STEG system but a pump is used, typically a 1/2 horsepower (.37kW) high head effluent pump, with 50-100mm piping buried to a minimum depth along the grade.

• Grinder pump pressure sewer system – a 2-horsepower (1.5kW) grinder pump located in a pump vault conveys wastewater slurry along PVC piping of 40-80mm to a centralized treatment system. This approach is not appropriate for a remote lodge facility unless a generator system is employed and power generation is regular.

Two main waste decomposition processes must be understood to evaluate a treatment process:

• Aerobic – uses oxygen (also called respiration). This process takes place in cells to convert biochemical energy from nutrients (i.e. wastes) into adenosine triphosphate (ATP) through catabolic reactions that involve the oxidation of one molecule and the reduction of another. These processes are generally fast and produce heat (exothermic) and typical applications include activated sludge, package plants, aeration ponds, most constructed wetlands applications, and composting.

C6H12O6 + 6O2 → 6 CO2 + 6 H2

68 Parten, 13

O

69 Parten, pg 48. 70 Parten, pgs. 67-70.

57

• Anaerobic – does not use oxygen (also called anoxic in wastewater terminology). Anaerobic processes are slower than aerobic reactions, but are widely used in wastewater treatment, particularly for the breakdown of sludge and/or for the capture of methane produced in the final cycle of anaerobic digestion; it is common in septic tanks, biogas digesters, and some constructed wetlands. Anaerobic digestion is also an unwanted side effect of landfills.

C6H12O6 → 3CO2 + 3CH

Grey water recycling

4

Residential greywater is comprised mostly of wastewater from showers, sinks, dishwashing, and laundry. It often contains high concentrations of easily degradable organic material, such as fat, oil and other organic substances from cooking, residues from soap, and tensides from detergents, and the level of pathogens is typically very low71. By maintaining two separate waste streams - grey water and black water - treatment regimens for both can be downsized and the resulting septic effluent and sludge processing requirements will be very small. Segregating black water may also allow the use of other technologies such as biogas digesters to treat primary wastes. Fundamentally, though, “Greywater is for reuse, not disposal.”72

Photo 49 Simple grey water collection system, Lamu.

Photo 50 Grey water treatment bed with Vetiver grass, Mombasa.

Grey water recycling is of three main varieties73

• Diversion – water is diverted directly to a garden or planted area. This is only appropriate for washing machines, laundry tubs, showers, hand basins and baths. A greywater diversion device (GDD) is a hand-activated switch that diverts untreated greywater by gravity or pump directly to a sub-surface irrigation system (minimum 100mm deep)

:

74

71 Ridderstolpe, pg. 1.

.

72 NSW Guidelines for Greywater Reuse, pg. 12. 73 NSW Guidelines for Greywater Reuse, pg. 4. 74 NSW Guidelines for Greywater Reuse, pg. 10.

58

• Treatment – water is treated for reuse such as toilet flushing, washing machine use, or surface irrigation. Treatment also allows reuse of kitchen grey water. A greywater treatment system (GTS) collects, stores, treats, and may disinfect, greywater75

• Bucketing – relatively small quantities of greywater are collected manually for irrigation. .

When grey water is separated in a remote facility, the following objectives can be met76

• Avoid the creation of odors, stagnant water, and mosquito breeding sites.

:

• Prevent eutrophication (oxygen depletion) of surface waters through nutrients loading. • Reduce or prevent contamination of groundwater and surface water reservoirs. • Use greywater as a resource for groundwater reclamation or landscaping. • Allow dramatic downsizing of wastewater treatment components such as piping, septic tanks or

package plants.

An important component of a greywater system is managing the load. This means both minimizing the input of toxins, detergents, cleansers, metals, or other components that will require removal, as well as reducing the quantity of water generated. At an ecolodge facility, this can be accomplished in a threefold manner: educating the visitors about the concept and the desire for conservation, providing only biodegradable soaps and cleansers, and installing low-flow showers, sink faucets, and taps, and eliminating or limiting bathtub options. In some facilities such approach is meaningless either due to the quantity of freshwater available or due to the level of service to be provided, but in lodges sited on the ocean or in arid landscapes, these concepts can have a significant benefit to both operating costs and environmental impact.

The following techniques can reduce the BOD load and treatment requirements for a grey water system77

• Equip kitchen sinks, showers, bath tubs, washing machines, and other equipment with screens, filters, or water traps.

:

• Install grease traps on all kitchen equipment to prevent clogging in the pipe system. • Use low phosphorus washing and dish-washing powders. • Liquid soaps containing potassium should be preferred to hard soaps (especially for systems

connected to landscaping or irrigation). • Chlorine should be substituted with biodegradable cleaning chemicals.

Ingredients to avoid in soap and detergent selection include the following78

• Bleaches or softeners (use oxygenated bleaches such as hydrogen peroxide instead)

:

• Detergents that advertise whitening, softening and enzymatic powers • Detergents which include:

o boron, borax, or chlorine, or bleach o peroxygen or sodium perborate o petroleum distillate or alkylbenzene

75 NSW Guidelines for Greywater Reuse, pg. 18. 76 Ridderstolpe, pg. 4. 77 Ridderstolpe, pgs. 4-6. 78 CA Graywater Guide, pg. 28.

59

o sodium trypochlorite

In very small systems, grey water can be collected in buckets or run from individual sources to different mulch beds or trees. In larger systems, small septic tanks may be desirable to reduce odors and remove oils and sludge. The following design criteria can be employed79

• Surface hydraulic load should be less than 0.5 m

: 3/m2

• Retention time should be more than 6 hours at maximum flow. , calculated from maximum expected flow.

• Sludge storage volume of about 50 kg per person a year can be used for rough estimation. Yearly sludge production will decrease due to mineralization and compaction if the time of retention is over one year.

The following components comprise a greywater diversion system80

• Hand-activated valve

:

• Switch or tap fitted to the outlet of the waste pipe of the plumbing fixture (e.g. a washing machine) • Coarse filter for screening out solids and oils/greases • Non-storage surge attenuation • Overflow device • Irrigation or distribution system

Ecosanitation

Ecological sanitation, commonly called ‘Ecosan’, is a wastewater theory and practice that aims to minimize the impact of waste through minimizing its generation, while actively recycling the nutrients contained in the waste stream. It accomplishes this through a flexible combination of technology and practices. Ecological sanitation is based on three fundamental principles81

:

Photo 51 Typical ecosanitation toilet with urine diversion.

Photo 52 Ecosanitation toilet with composting chamber and vent.

79 Ridderstolpe, pg. 8. 80 NSW Guidelines for Greywater Reuse, pg. 10. 81 Ecological Sanitation, pg. 4.

60

• Preventing pollution rather than attempting to control it afterwards. • Sanitizing urine and feces. • Using the safe products for agricultural purposes.

Accomplishment of these goals is achieved primarily by segregating urine and feces, so that they can be treated separately. This also allows two options for feces processing: dehydration or decomposition. This ‘primary processing’ occurs in special toilets by diverting the urine and feces into separate containers, where it is then contained for a given period, typically 6-12 months. During this containment the number of pathogens will decrease, and decomposition, dehydration via ventilation and the addition of dry material, and increased pH through addition of ash, lime, urea, as well as the competition for nutrients by other organisms. Secondary processing is a means to make feces safe enough to return to the soil. This step can include further treatment by high temperature composting, increasing pH with urea or lime, longer storage time, or disposal into a biogas reactor82

As mentioned, urine separation is an important component of ecological sanitation systems. The following concepts explain the advantage of diverting urine to a separate tank and storing one month

.

83

• This reduces the volume of fecal material which contains the pathogens. :

• The urine remains relatively free from pathogens. • Urine and feces require different treatments. • This allows dehydration of feces, thus simplifying pathogen destruction. • It reduces odor. • It prevents excess humidity in the feces processing vault. • Urine is a good fertilizer.

Composting toilets

A composting toilet is usually a self-contained unit that breaks down toilet wastes through aerobic digestion to 10-30% of original volume. This may involve urine separation, fan drying, or both. These toilets are ideal for sites where water availability is at a premium, such as desert or marine locations, where impact to the site should be minimal, or where there is a need or desire to capture nutrients from the waste.

82 Ecological Sanitation, pgs. 13-14. 83 Ecological Sanitation, pg. 58.

61

Photo 53 Self-made composting toilet on Lamu Island, Kenya.

Photo 54 Composting toilet on Bua River, Malawi.

Composting toilets are of two main varieties84

• Continuous, single chamber – excrement is added to the top, and the end-product is removed from below. These are typically premanufactured.

:

• Batch composters – two or more chambers that are filled over time, then allowed to cure without addition of new excrement. This approach is typical of home-built units.

Composting toilets have the following advantages:

• Dramatically reduce domestic water consumption. • Minimize the quantity and strength of wastewater. • Very low power consumption. • Faster decomposition (aerobic) than in septic system or biogas reactor (anaerobic)

The following disadvantages are noted:

• Maintenance requirements may be higher than a more conventional wastewater system. • Cleanout is unpleasant if the system does not operate properly. • Must be used in conjunction with a greywater system. • Smaller units may have limited peak load capacity. • Aesthetic issues including odor and unsightliness. • Toilet may produce a leachate which must be processed. • Most do require a power source.

The following parts constitute a composting toilet:

• Composting chamber. • Dry or micro-flush toilet, with our without urine diverter. • Screened air inlet to provide oxygen for aerobic digestion. • Exhaust system (often fan-forced) to remove odors and heat, CO2

84 EPA Water Efficiency Technology Fact Sheet - Composting Toilets, pgs. 1-4.

, water vapor, and byproducts of aerobic digestion.

62

• Inspection/maintenance/access portal. • Leachate drain (optional). • Mechanical mixer (optional).

As the process is aerobic, proper aeration of the mix must be maintained. This can be accomplished either by mechanical stirring (manual or automated), or by adding a structural material to the substrate on a regular basis. This can be wood chips, sawdust, leaves, thatch, or some other bulky, but biodegradable, material.

Biogas

‘Biogas’ is the popular term for methane produced biologically through anaerobic fermentation of organic material under controlled conditions, though the gas ranges from 50-65% methane (CH4)and 35-50% carbon dioxide (CO2

). A biogas reactor is a vessel much like a septic tank but which is specially designed to facilitate input of a substrate, to allow anaerobic digestion of that substrate to occur in an optimized manner, and to allow the controlled output of the biogas and inert slurry. Because this is an anaerobic process (e.g. without oxygen), it is typically slow and does not produce much heat. As a result, biogas may not be an appropriate waste solution in cold regions.

Photo 55 Biogas digester under construction, central Rwanda.

Photo 56 basic biogas cooking element.

Biogas reactors have the following advantages at a remote lodge site:

• Controlled breakdown of vegetable, toilet, garden, and other organic wastes. • Relatively simple to build and operate • Produces a slurry high in nutrient content for plants. • Produces a gas which is useable for cooking, operating an incinerator, lighting, or in some cases,

electricity production • Powerful demonstration project for local communities, especially where fuel wood is expensive and

deforestation is common.

However, there are several drawbacks to this technology:

• It will not work with a conventional high flow toilet. • Some users may find the concept distasteful.

63

• It must have a reliable flow of substrate to operate efficiently. • Some systems are problematic for reliable fuel supply for cooking due to gas production, gas line

fouling, or incompatible burners. • May require too much water for very dry areas. • May not operate efficiently in cold or seasonally cold areas.

There are four main stages in anaerobic digestion:

1. Hydrolysis – organic polymer chains are broken down into their smaller constituent parts such as simple sugars, amino acids, and fatty acids.

2. Acidogenesis – further breakdown of the remaining components by fermentative bacteria 3. Acetogenesis – the simple molecules created through acidogenesis are further digested to

produce acetic acid, carbon dioxide and hydrogen. 4. Methanogenesis – the intermediate products of the preceding stages are converted into

methane, carbon dioxide, and water.

Types of biogas reactors suitable to the small scale85

• Batch reactor – these are the simplest reactors, typically consisting of a box with a removable lid and gas line, and perhaps a stirring handle. These reactors are designed to operate in one cycle (batch) and then be emptied, but this process allows very high concentration wastes, making it suitable for application in arid regions. This approach may also be useful in cases where the digester has a dedicated use such as waste incinerator pre-combustion, and a batch approach is useful to produce gas at intermittent times and to process sludge or other byproducts from the solid waste management system.

:

• Fixed dome reactor (‘Chinese’ reactor) – these are common designs found in Kenya, Uganda, and Rwanda, consisting of a round dome of fired brick, ferrocement, or concrete located on a round masonry wall, with a flat or concave floor, thus approximating the shape of a sphere with available masonry materials and skill levels. In china these are designed to be operated in two modes concurrently:

o Batch mode, where precomposted agricultural wastes are loaded every 6 months o Semi- continuous mode, in which manure and human waste is fed daily

Unless there is an exterior gas storage container such as a floating lid tank or an inflatable bag, gas production and pressure can become high, resulting in digester leakage and difficulty with combustion downstream. Despite the often exact replica of the Chinese designs found in Africa, most African bioreactors are operated as plug flow – see below.

• Plug flow reactor – this reactor is designed linearly as an elongated horizontal cylinder, where length = 3x to 14x depth. This arrangement allows a longer detention time of the solids with more complete digestion before exit, compared to a fixed dome reactor, and the feed concentration can be higher. In plug flow systems, some of the effluent must be recirculated to inoculate the input substrate and maintain reactor efficiency86

85 Nijaguna, pgs. 7-12.

.

86 Nijanguna, pg. 50.

64

• Series reactor – these are typically fixed dome reactors in series, which approximates the design of the plug flow reactor. Additionally, the differentiated domes in series allow different bacteria to predominate in each, leading to higher efficiencies and more thorough digestion. This ‘phase separation’ effectively separates hydrolysis, acetogenesis, and acidogenesis in the first reaction vessel and methanogenisis in the second. Several tangible benefits are realized in a series reactor87

o Because acid formation in the first reactor occurs more quickly than methane production in the second, the loading rate in reactor one will be higher and the unit can be sized smaller.

:

o Acidogeneic organisms thrive in a low pH of 5-6, whereas 7-8 is more efficient for methanogenic bacteria.

o The process is more stable.

The following empirical principles are valuable when designing a biogas reactor88

• Height =1.3x diameter for dome reactors.

:

• Round tanks are the most efficient for construction and thermal control as they have the highest volume to surface ratio.

• The fermenter (final) tank should be completely airtight to optimize methanogensis and reduce the hazard of explosion.

• Position inlet and outlet such that the path between them is the longest possible with no ‘short circuit.’

The following equations can be used to size a biogas reactor89

:

V1 volumetric methane production rate in m3/m3

B of digester

0 ultimate methane yield in m3 of CH S

4 0 influent volatile solids concentration in kg/m

HRT Hydraulic Retention Time in days 3

μm K dimensionless kinetic coefficient

maximum specific growth rate of microorganism per day

V2 HRT Hydraulic Retention Time in days

digester volume

LR loading rate

87 Nijanguna, pg. 93. 88 Nijanguna, pg. 108. 89 Nijanguna, pg. 115.

65

Septic tank

The septic tank is a common wastewater primary treatment unit which can be used alone or in combination with other processes to treat raw wastewater before it is discharged to a subsurface infiltration system. Septic tanks are covered and watertight, rectangular, oval, or cylindrical, and are typically buried. Septic tanks store and partially digest settled and floating organic solids, thereby forming sludge and scum layers, which can reduce the sludge and scum volumes by as much as 40%. Inlet and outlet pipes are typically ‘Tees,’ which slow the incoming wastewater and retain the sludge and scum layers, drawing effluent from a clarified zone or treated water. Outlets will often have an effluent screen (or ‘septic tank filter’) to retain solids. Inspection covers are provided to allow access for periodically removing the tank contents, including the scum and sludge90

.

Photo 57 Typical septic tank sizing for two cottages and low-flush toilets.

Photo 58 Septic tank details, including T's to reduce flow velocity and facilitate settling.

The following processes occur in a septic tank91

• Solids from the wastewater accumulate in sludge and scum layers in the septic tank.

(compare with biogas digester steps, below):

• These solids undergo liquefaction. • Acid-forming bacteria partially digest the solids by hydrolyzing the proteins and converting them

to volatile fatty acids. • Most of the fatty acids are dissolved in the water phase (‘clarified zone’). • These acids are able to pass from the tank in the effluent stream, reducing the efficiency of the

septic tank. • Methanogenisis, in which the volatile fatty acids are converted to methane, usually does not

occur to a significant extent because temperatures are too low. However,

The following parameters are important for septic tank design92

90 EPA Onsite Wastewater Treatment Systems Manual Revised 2002, pg. 4-37.

:

91 EPA Onsite Wastewater Treatment Systems Manual Revised 2002, pg. 4-38. 92 Parten, pgs. 88-91 and Onsite Wastewater Treatment Systems Manual Revised 2002, pg. 4-41.

66

• Sufficient volume – the middle horizontal zone in the tank (between sludge on the bottom and scum on the top) should at least equal the daily predicted discharge coming into the tank, to provide a 24-hour retention time.

• Adequate depth – 1:1 width to height ratio is typical. Higher is better, as this will prolong sludge build up duration and lengthen the maintenance interval.

• Septic tank length to width ratio – 3:1 is recommended. • Multiple compartments in series, connected with ‘T’ fittings and a vent – two to three compartments

are typical (or more for very large systems) to retain sludge and fats/oils/grease before discharge. The first compartment should be 1/2 to 2/3 the size of second compartment in a double chamber tank. These compartments should be connected with ‘T’ fittings (‘T’ located on inlet side) to reduce water velocity and prevent solids from settling directly under the Tee. A vent should be installed to allow pressure balancing between gases on both sides.

• Water tight – excess water entering will overload the tank, and water escaping will short circuit the treatment system. The tank should be filled with water before backfilling to test water tightness.

• Structural integrity – the tank should be built to withstand corrosives, pressures, and possible movement of fittings due to pumping or maintenance.

• Inlet Tee – water is directed in and down, underneath the surface, to minimize disturbance to the water body that might delay settling or promote settling closer to the outlet.

• Outlet Tee – this prevents scum and solids from exiting the tank, the descending leg should extend to 30 or 40 percent of the liquid depth and the ascending leg should extend 15cm above the liquid level to prevent the scum layer from escaping.

• Outlet should be at least 23cm below roof of tank to allow scum storage and ventilation. • An effluent filter (or ‘outlet screen’) should be installed on the descending leg of the outlet to reduce

solids buildup downstream. This screen should be accessible for cleaning.

For septic tanks connected to kitchens, the following guidelines are recommended:

• Do not use a sink garbage disposal or garbage grinder. All food wastes should be separated and composted.

• Likewise, a strainer on the sink or an inline settling vessel is recommended to reduce food input to the septic tank.

• A grease trap or interceptor is necessary to remove fats/oils/greases.

67

Grease trap

Greases and oils, particularly from kitchens, pose many problems for the wastewater system. They will clog pipes as the material cools and solidifies, particularly on T’s and L’s in the system. Greases are not easily broken down in the anaerobic conditions of the septic tank, and so they will produce more sludge. These can be constructed similar to a small septic tank, and they should be fitted with a ‘flow diverter’ to reduce water velocity and allow cooling of hot water containing emulsified grease

Photo 59 Simple grease traps in series on Shire River, Malawi.

Photo 60 This material will foul a wastewater treatment system, but it can be incinerated for heat or biodigested.

Grease trap sizing can be done according to the following steps93

1. Calculate the number of ‘Fixture Units’ in the system:

:

3 basin sink 3 units 2 basin sink 2 units Dishwasher 4 units Wok stove 4 units

Floor drain 50 / 80 / 100mm 2 / 3 / 4 units Floor sink 80 / 100mm 3 / 4 units

2. Calculate the minimum Flow Rating = Fixture Units • 12 liters/minute 3. Calculate the minimum Grease Trap Capacity = Flow Rating • 12 minutes

Alternatively, manufactured under sink grease separation/interceptor units are available that are either dedicated to a particular sink / machine or can be plumbed from multiple sources. These can typically handle 60-180 liters/minute.

Grease removed from the system in this manner can be stored in 200 liter barrels in the waste segregation area, and eventually be turned into biodiesel fuel, composted, or incinerated.

93 Austin Texas Water Utility Special Services Division

68

Subsurface wastewater infiltration system

A Subsurface Wastewater Infiltration Systems (SWIS) is the most common technique for treating wastewater on site, and the simplest form of these is the ‘soak pit’. However, soil must be permeable, or imported fill material must be used to achieve infiltration. A variety of physical, chemical and biochemical processes and reactions occur in the treatment process, and these are determined by the soil type, effluent type, and depth of the system.

A soak pit is a simple means by which to disperse water back into the ground. Unlike a leach field which is oriented horizontally, the soak pit is simply a removed column of soil. Because deeper soil strata are not rich in bacteria, a soak pit does not achieve the same biological processing of wastewater as a leach field. Nonetheless, because of the relatively minor wastewater amounts generated, many ecolodges can operate with a standard soak pit.

A leach field is a horizontally oriented system, where both biological and mechanical filtration occurs.

Package plants

Package plants are premanufactured systems that are designed and optimized to process wastewater in a very small volume with a minimum of user operation and maintenance. They are becoming the norm for European and North American onsite treatment systems as septic tanks become less permissible due to newer environmental legislation, and many manufacturers have units suitable for remote conditions. There are three main types of package unit:

• Aerated Treatment Unit (ATU) – designed to oxidize both organic material and ammonium-nitrogen (to nitrate nitrogen), decrease suspended solids concentrations and reduce pathogen concentrations94

• Continuous-Flow, Suspended-Growth Aerobic Systems (CFSGAS) – uses an aerobic suspended-growth process (e.g. activated sludge) by recycling settled biomass back to the treatment process. This converts soluble and colloidal biodegradable organic matter and some inorganic compounds into cell mass and metabolic end products, which are separated from the wastewater in a clarifier. Most designs are capable of providing significant ammonia oxidation and effective removal of organic matter

.

95

• Fixed-film systems (FFS) – biological treatment processes that employ a medium such as rock, plastic, wood, or other natural or synthetic solid material that will support biomass on its surface and within its porous structure

.

96

However, they are expensive, can require large amounts of electricity, and most importantly, as optimized biological systems, they do not operate well in conditions of intermittent use, when no ‘food’ is available to the bacteria population. For this reason, they may not be the best choice for seasonal safari lodge operations.

.

Rotating Biological Contactor (or ‘rotating disk’) is a manufactured wastewater treatment unit that maintains a bacteria population (‘fixed film’) on a series of coaxial disks spaced very closely to maximize

94 EPA Onsite Wastewater Treatment Systems Manual Revised 2002, pg. 4-52. 95 EPA Onsite Wastewater Treatment Systems Manual Revised 2002, pg. TFS-1. 96 EPA Onsite Wastewater Treatment Systems Manual Revised 2002, pg. TFS-7.

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total surface area in a small footprint. They operate by rotation of the bacteria culture through an effluent bed to promote aerobic conditions with minimal energy input. These units can be sized according to flow rate, or multiple units can be used in series, which promotes the growth of different bacteria in the subsequent stages, allowing a more efficient process97

Sequencing batch reactors (SBR) and continuous flow aerated tanks are manufactured units that maintain the bacteria population on the surface of thousands of small plastic pellets which circulate thought the effluent while air is bubbled into the mixture from pumps and diffusers. A continuous flow system will incorporate different compartments for better efficiency, whereas the SBR will process the effluent in a series of steps within the same chamber. An example of the different steps (for either process) is listed below

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1. Effluent enters from the primary treatment (i.e. septic tank)

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2. Aeration and mixing is performed by mechanical blowers and/or diffusers (~20-22 hours) 3. Sludge is allowed to settle (~2-4 hours) 4. Effluent is removed to soil dispersal system

Intermittent sand filters

These are simply large scale slow sand filters, where a treated effluent stream is regularly ‘dosed’ through the sand bed throughout the day, thus maintaining an aerobic environment. Advantages are listed below99

• Simple, low cost, and minimal operating energy – they require only 5-10% of the electricity necessary for a package unit, or in some cases, they can operated purely on gravity.

:

• Tend to be much more consistent in discharge • Are more resilient to surges in effluent quantity or quality. • Less susceptible to operational slowdowns than package units. • Long service life with less often and less complex maintenance. • Lower sludge production. • Effluent is typically colorless and odorless.

Disadvantages include the following:

• Requires more area than a package unit. • Unfamiliar technology. • Some areas may not have a suitable sandy filter media, though some recycled materials such as

crushed glass have been found to work well. • Requires skilled construction.

97 Parten, pg. 143. 98 Parten, pgs. 145-146. 99 Parten, pgs. 199-205.

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Constructed wetland

Constructed wetlands are a preferred method for secondary treatment because they are effective, attractive, and require little or no energy input. Disadvantages are that wetlands require a fairly large area with a rectangular footprint, and they are not suitable to areas with steep topography or heavy seasonal rains. Additionally, they do not perform as well in cold conditions.

Photo 61 Constructed wetland in Liwonde National Park, Malawi.

Photo 62 Constructed wetland for a housing estate, Mombasa.

Subsurface flow wetlands have the advantages that treatment occurs below the surface of the treatment media, resulting in less odor, lower maintenance, and lower health risk. However, they are susceptible to water level changes, and if installed in areas of heavy seasonal rains, then some additional storage capacity or level control must be included in the design, though this may reduce the effectiveness of the system100

Free water surface wetlands are constructed wetlands divided into a minimum of three zones

. Due to their exclusively anaerobic treatment process, they are not very effective at nitrogen reduction, and in most cases, subsurface flow wetlands should be combined with a trickling filter or free water surface wetland to reduce nitrogen levels.

101

• First pond is fully vegetated with macrophytes (cattails or bulrushes) - the influent is suspended and colloidal solids are flocculated and settled under anaerobic or anoxic conditions.

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• Middle pond has and open water surface, which performs like a facultative lagoon – this re-aerates the anaerobic wastewater for aerobic biodegradation and possible nitrification

• Last pond is fully vegetated with macrophytes – performs additional flocculation and sedimentation (and denitrification).

Stabilization ponds are large basins filled with wastewater which undergoes some combination of physical, chemical, and/or biological processes. They are not common in developed countries because of the large area they require, the need for fencing to keep animals and people out, and because discharged water must often undergo some additional treatment to meet more stringent water quality standards. However, these systems are still widely used in Africa.

100 Parten, pgs. 234-235. 101 Onsite Wastewater Treatment Systems Manual Revised 2002, pg. TFS-37.

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These wetlands have the following characteristics102

• Large in size compared to other systems.

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• Perform best when segmented into at least three cells. • Obtain necessary oxygen for treatment by surface reaeration from the atmosphere. • Combine sedimentation of particulates with biological degradation. • Produce large quantities of algae, which limit the utility of their effluent without further treatment.

Facultative ponds or lagoons are the most common form of lagoon technology. The water layer near the surface is aerobic, the middle layer is aerobic near the top and anaerobic near the bottom (this constitutes the ‘facultative zone’), and the bottom layer, including sludge deposits, is anaerobic. These are not ideal wastewater treatment systems: they are large in size, expensive to build, perform only a portion of the treatment necessary for surface discharge, and produce large concentrations of algae, making them incompatible with subsurface wastewater infiltration systems. They are recommended only as an alternative when a SWIS is not feasible, usually for to surface waters, which is generally unacceptable.

Aerated lagoons use mechanical equipment (typically paddles or fountains) to accelerate biodegradation. They are typically deeper than other lagoons, possible via the active aeration. They do not produce the intense algal load on downstream processes and have a smaller footprint than a facultative pond. However they require a high energy input as well as maintenance. For this reason they would have only limited application in remote lodge context, unless perhaps a particularly windy location could be utilized to achieve mechanical aeration.

Passive dosing methods are inline devices that serve to store wastewater in a given quantity and release it in intervals, instead of a constant flow. This is useful to allow aerobic conditions in the treatment media, whether it is a soil, wetland, or other matrix, by avoiding the saturation that would come from continuous flow or the larger interval of dosing from a flush system.

Dosing chambers should have the following specifications103

• Allow approximately 5 litres/m

: 2

o reasonable retention time in bed on each dose:

o prevents surface (anaerobic) ponding o provides enough momentum to pass down all pipes evenly.

• The dose volume is determined by the height at which water overflows into the box chamber and the autosiphon triggers – this should be adjustable

102 Onsite Wastewater Treatment Systems Manual Revised 2002, pg. TFS-37. 103 De Mowbray, RBTS Design & Construction, powerpoint presentation.

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Percolation test

A percolation test is performed to determine the soil’s capacity to absorb water from the wastewater system, whether it is in the form of a leach field or a soak pit. The following suggestions apply to percolation testing104

• At least two holes should be dug. More tests should be conducted based on the proposed area of the field or if different soil types are found in the location of the field (e.g. in a sloped field that may go through different strata).

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• Hole should be as deep as the proposed field or soakaway, or 30cm minimum • 15-30cm in diameter. • Scarify the sides of the hole with a nail or machete. • Add 5cm gravel evenly to bottom of hole. • Use clean / clear water for testing.

The percolation test procedure is as follows:

1. Add water at least 30cm above the gravel and wait 15 minutes. a. If the water is still visible, maintain 30cm of water in the hole for 4 hours, then let hole drain

for 12 hours before proceeding to the next step. b. If the water is drained after 15 minutes, proceed to the next step.

2. Fill the hole to 15cm over the gravel, and mark this location with a nail. 3. Measure the drop in water level for 2 hours or until the change is less than 3mm, whichever is later.

a. For slow draining soil (a from above), note level drop every 30 minutes b. For fast draining soils (b from above), note the level every 10 minutes. c. For extreme cases other intervals can be chosen, i.e. 1 hour or 5 minutes. d. Add 15cm of water when the level drops to the gravel to achieve a 2 hour record.

104 Parten, Recommended Percolation Test Procedures.

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SOLID WASTE MANAGEMENT

Waste production is an inevitable component of a tourist facility of any kind, and it is typically higher with a higher level of service. Wastes can be solid, liquid, and gaseous. Gaseous wastes will come from incineration of solid wastes and from combustion of petroleum products from cooking, electrical generation, some refrigerators and freezers, and vehicles. Liquid wastes are typically from cooking and toilets; these are considered in the wastewater section of this document. Solid wastes are comprised mainly of the packaging and containers used for purchasing food and drinks.

Obviously, reduction of packaging is the best solution for minimizing solid waste production. This can be accomplished by purchasing foods in bulk and buying as much produce, meat, and grains as possible in local markets. However, bottled water seems inescapable in the African tourist industry, and numerous beverages and other foreign foods such as cheeses, cereals, and cookies will come in variety of paper, plastic, or foil packaging. Additionally, all industrial products used at the lodge will have large quantities of associated packaging.

Segregation Area

Segregation is the separating of wastes at the point of discard. This process divides wastes into recyclables (steel cans, glass bottles, and plastic water bottles), compostable (paper, cardboard, and food wastes), those which must be buried or incinerated (tetra packs, plastics, coated cardboards, and Styrofoam), and hazardous wastes (batteries, oil and fuel containers) which should be removed from the site. An ecolodge facility should have a dedicated, enclosed room or roofed compound for this purpose, to both maintain a fixed destination for all trash, to keep away moisture, and to prevent animals such as monkeys and baboons from scavenging in the material.

One particular material of interest is waste oils, from both cooking and machinery. This material can be very damaging in other systems such as composting piles or bioreactors. However, it also has a high resale value, and it should be segregated into types so that it can be returned to local trading centers for resale and reuse.

Location of segregation area:

• Centralized location near staff housing or mechanical area. • Away from direct runoff zone to local river or stream. • Access by vehicle for loading oil containers or boxes. • Covered and fenced to keep out rain and animals.

Segregation containers are as follows:

• Oils – stored in 200 liter drums o Cooking oils – removed from oil/fat skimmer on kitchen grey water system o Machinery oils – taken directly from mechanic after oil changes and strained into vessel

• Composting materials – directly into mechanical composter or compost pile • Paper and cardboard – stored in a box and shredded before composting • Foils, plastics, and coated papers/cardboards – stored in a box before incineration or removal • Hazardous wastes – stored in sealed container for removal from site.

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Composting

Composting is a biological process in which microorganisms break down a material into simpler compounds in the process of water and oxygen. Compostable materials (called substrate) include paper and cardboard, food residues, coffee grounds and filters, tea bags, landscaping materials, egg shells, and sawdust from woodworking. In more advanced wastewater processes, even sewage sludge can be composted to reduce its volume and toxicity.

Compost must have substrate, moisture content, and air voids to proceed, and the balance of these constituents determines the speed of decomposition. In a remote facility where not a tremendous amount of material is being processed, this rate of decomposition is not critical, but the process of ‘turning’ the wastes to assist mixing and aeration is a simple and easy means to accelerate decomposition. This can be accomplished manually with forks and shovels or more easily by rotation in a manufactured composting container. Often, composting is assisted by the inclusion of a structural material such as wood chips, shredded cardboard, plant stems, or thatch wastes, which promotes air voids in the substrate.

Incineration

Incineration is an option in very remote facilities where removal is not economically feasible, or in areas where removal is not a more ecologically sound option (for example where transport to the local municipality would result in open dumping or disposal in a river course). Many options exist for waste incineration, but the Demontford incinerator used in medical waste combustion and promoted by the World Health Organization is recommended as a viable and proven option for remote lodges. Note that PVC or any chlorine-containing wastes should not be incinerated, as this produces Dioxin and furan emissions105

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Photo 63 Municipal waste incinerator made from locally fired bricks, Nchisi, Malawi.

Photo 64 De Montford incinerator made with compressed earth blocks, Malawi.

105 IT Power India, pg.7

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A Demontford incinerator operates on a double combustion principle106

The burning cycle contains three phases

: “Waste is warmed, dried and melted in the primary combustion chamber, before being burnt at the grate in the primary combustion chamber. Partially burned flue gas and particulates are drawn from this primary area into the secondary chamber, where additional air induces secondary burning before the flue gases are evacuated into the atmosphere through the chimney.”

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1. Preheating period: the primary chamber is loaded, lit and the temperature indicated on the stove pipe thermometer brought to approximately 600° C in 20 to 30 minutes by burning a fuel such as firewood, cardboard, or thatch, which is supplemented by kerosene, diesel fuel, or biogas if necessary.

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2. Waste disposal: plastic and foil wastes are loaded at a rate that maintains a constant fire in the grate (approximately 6 kg/hr). This loading should not be performed too rapidly, and combustion above 900° C should be avoided since this increases exhaust gas velocity and reduces secondary combustion, inducing a dense black smoke.

3. Burn down/close down period: Eight to ten minutes after the final plastic waste is loaded, an additional 1 to 2 kg of fuel is added to ensure that complete burning occurs.

To reduce emissions, adhere to the following practices108

• Rigorously segregate waste so that no PVC waste is incinerated.

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• Ensure that the incinerator is built according to recommended dimensions, using appropriate materials, and that it is functioning properly, and the chimney is clear of excessive soot.

• Ensure that the incinerator is preheated adequately and that supplementary fuel is added whenever necessary to maintain the burning temperature above 600°C.

• Load the incinerator according to the recommended “Best Practices”. • Minimize burning in the chimney through correct loading practices and regulation of the self-

adjusting draft control in the chimney. This increases the gas residency period. • Adopt rigid quality control measures including staff training, record keeping, and regular operation

inspection.

The incinerator should be built at a location where109

• It is convenient to use.

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• It is not close to tourist areas or occupied or planned buildings. • There is no chance of flooding. • No flammable roofs or inflammable materials are stored within a radius of 30 meters. • Prevailing winds blow smoke away from buildings. • Security risk is minimized.

106 IT Power India, pg.4 107 IT Power India, pg.5 108 IT Power India, pg.9 109 IT Power India, pg.10

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Landfilling

Traditional landfilling is possibly the cheapest option available for solid waste management, but if the landfill is constructed to modern standards it is a rather complex and costly option. A traditional landfill (called a Natural Attenuation landfill) was constructed without a bottom liner or compacted clay layer, as percolation through the soil was assumed to be sufficient for bacteriological decomposition of liquid waste from the landfill110

A containment landfill should have the following components from the bottom

. This is now known to be untrue for organic pollutants, so modern landfills must be lined (called Containment Landfills).

111

• Clay liner of bentonite clay 1.2 to 1.5m thick

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• AND/OR Flexible Membrane Liner (also called Synthetic Membrane Liner) of PVC, CPE, LDPE, LLDPE, VLDPE, HDPE, or other approved polymer. HDPE (High Density Polyethylene) is preferred, minimum 30mil / .762mm thick)

• Granular leachate collection layer • Geotextile layer • 15cm soil backfill • Waste placed in layers .6 to .9m thick and compacted with a tractor or other mechanical device to a

density of 500-900 kg/m3

• Layer of soil .15 to .3m to complete a lift, lifts continue to the design height of the landfill. until a ‘cell height’ of 2.4m is reached.

• Landfill cap of same or better impermeability as the bottom layer.

Both leachate and landfill gas (biogas from anaerobic digestion) will be produced by the landfill during its time operation and afterward for a period of many years. The gas can be explosive if not collected, and the leachate will become more concentrated over time. This leachate can contaminate local surface and groundwaters. Technical piping systems are installed in modern landfills to collect gas and leachate and process it by burning or biological/chemical treatment. Because of the cost, complexity, and long term duration of solid wastes when landfilled, this technique is not recommended for remote ecolodge sites. However in some areas it may be viable to improve solid waste management practice in the local community.

Removal

Removal is one of the simplest options available to a lodge, but it may not be environmentally sound. Assuming that regular trips are made into the local community to buy provisions, then waste can be transported out on these trips, assuming that the volume is not excessive (obviously, the amount of waste generated will be smaller than the amount of foodstuffs and other materials purchased).

However, most municipalities of any size in Africa do not have modern solid waste management system (including waste segregation, recycling, composting, sanitary landfilling, and/or incineration), but instead practice open dumping into unlined landfills (where substantial amounts of leachate are produced from precipitation and this material contaminates local surface or subsurface waters. For this reason, waste disposal off site should be thoroughly investigated before it is practiced.

110 Lindeburg, pg 31-2 111 Lindeburg, pg 31-4

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HOT WATER SUPPLY

Hot water is typically an essential component of a high end tourism resort, but in some locations it can be omitted due to clientele level or ambient temperature. Assuming that it is prerequisite, it can be a major energy demand for the facility. For this reason, alternatives to the conventional approach of electric geysers should be explored from the beginning.

In most situations, a solar hot water system with an electric, propane, or wood fired backup is the best choice for remote locations in Africa, assuming sun is regularly available (exceptions would be mountain lodges or unique regions with heavy fog). In this case, the following questions will assist in planning the system112

• Is the roof or proposed collector area and collector temperature sensor shaded by trees daily or seasonally?

:

• What is the best orientation and angle of the collector?

• What is the future access for maintenance or replacement?

• Will birds, monkeys, or other fauna affect the collectors?

• What is the shortest possible path to the insulated storage tank?

• Can the roof structure carry the collector/storage tank load?

• Is insulated piping available?

• What is the available or preferred auxiliary heating, and how will it be coupled with the solar hot water system?

The following values can be used for estimating usage113:

Activity Liters/use Hand washing 3 Shower (40°C) 35 Bathing (40°C) 120

Dishwasher (50°C) 20 Washing machine (50°C) 30

Alternatively, the following table can be used:

Consumption level Liters/day/person Low 20-30

Moderate 30-50 High 50-70

Of course, these figures do not account for specialty uses such as heated plunge pools or multiple nozzle showers that may be installed in very high end facilities.

112 Planning and Installing Solar Thermal Systems, pgs. 55-56. 113 Planning and Installing Solar Thermal Systems, pg. 60.

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Calculations of flow are important in sizing tankless water heaters. The following table can be used114:

Flow (l/m)

Item Low High Low-flow faucet 1.9 5.7

Standard faucets 3.0 9.5 Low-flow showerheads (<9.5l/m) 4.5 9.5

Standard showerheads 9.5 13.2 Dishwashers 3.79 7.6

Washing machine 7.6 15.1 Standard bathtub 15.1 18.9

Solar

Solar hot water is the obvious solution for hot water in remote facilities, and they are becoming much more common in eastern and southern Africa as more vendors import units, the price lowers, and they are perceived as suitable technology by both the wealthy and poor populations. However, units available in Africa are often not the highest quality, and maintenance, repair, and parts replacement are complaints voiced by many solar water heater owners. It is advised to research available products thoroughly, and in some cases import directly for better pricing and durability in remote conditions.

Photo 65 Evacuated tube solar hot water collector, Lake Victoria, Kenya.

Photo 66 Locally made solar hot water concave tube collector, Lamu Island, Kenya.

Solar water heaters can be active or passive:

• Active system – employs a pump to circulate the Heat Transfer Fluid between the collector and the storage tank. These have some advantages:

o The storage tank can be situated lower than the collectors. o Can use a conventional electric geyser as storage. o Typically more efficient.

Passive system – these use either a collector/storage unit or a convective thermosyphon effect between collector and storage tank. Passive systems are more common in Africa, where they operate on gravity feed. 114 Puffer, Homepower #118, pg. 74-79.

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They can also be open loop or closed loop, determined by whether the fluid in the collector is the hot water that will be delivered to the user. Closed loop systems with use water with an antifreeze where the potable water to the user is heated by a heat exchanger.

Five main types of solar water heating systems are available115

• Thermosyphon – these are the most common product in Africa, evidenced by the tank located directly above the collector. In warm climates, these systems are open loop, and the water enters the bottom and exits the top as with a batch system, whereas in cold climates a closed loop must be used. These systems are very heavy.

:

• Batch – ICS (Integrated Collector Storage) – collector and storage tank are combined; cold water enters the bottom of the tank as hot water is drawn from the top. Low-cost and simple in moderate climates, however the tank is not insulated so hot water is not available in the morning.

• Open-loop direct system – the simplest active system, where a standard electric tank (geyser) is connected to a thermal collector. A small 10W solar pump can be used to circulate water, or an AC pump with a control module. These systems are well suited to mild climates with allot of sunshine.

• Pressurized glycol system – an active, closed-loop system where potable water is routed only to the storage tank, and a HTF mixture circulates from the collectors to the tank. This system requires an expansion tank as well as other components for filling, venting, and maintenance. The advantage of this system is that the collectors can be mounted in a discrete location away from the storage, and they operate without problem in cold environments.

• Closed-loop drainback system – this system uses distilled water as the HTF, which is stored in a reservoir tank below the collector when not in use. When water is needed, a pump circulates the distilled water through the collector to a heat exchanger, which then heats the delivery water. These systems have the advantage of minimal maintenance and maximum longevity of the system, however they are hard to power with a pure DC system, and the drainback feature is not necessary in mild climates.

115 Patterson, John, Solar Hot Water Basics and Marken, pg. 94.

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Photo 67 Flat plate collectors with electric geyser element and room for expansion, Malawi.

Photo 68 Evacuated tube collectors with ball cock style low pressure geyser, Malawi.

Solar water heaters typically have the following parts116

• Collector – plates, copper tubing, or evacuated tubes inside an insulated and glazed box, typically 1.2m x 2. m, to maximize the heat transfer from solar energy to the HTF.

:

o Flat-plate – 7-10cm thick, black, and covered with glass, typically cheap.

o Evacuated tube – glass tube with vacuum surrounds individual pipes.

eliminates influence of ambient air temperature perform better in cloudy weather can achieve higher temperatures more expensive

o Integrated Collector Storage (ICS) / batch collector – combines solar collector and storage tank. Has greater depth than flat-plate collector -15 cm. A simple batch heater can be a tank within a glazed box, and is a good system when requirements are low.

• Collector Mounting System – a mounting system should be chosen based on the existing structure and roof type, the availability of sun, and whether the unit should be disguised or hidden.

o Roof mount – metal brackets usually parallel to and slightly above roof

o Ground mount – posts or truss structure just above ground or elevated, typical system when units should be hidden.

o Awning mount – attaches to a vertical wall and can be adjustable for tilt.

• Storage tank – an insulated water vessel of 50l -300l, may come with integral heat exchanger or electric element, depending on the system, and may be integral to the collector unit.

• Heat Transfer Fluid (HTF) – hot water from the tank (open loop), or a fluid containing anti-freeze and a corrosion inhibitor (closed loop), either pumped (active system) or driven by natural convection (passive system). Three HTF types are typical:

o Potable water – to be heated and used

o Distilled water – closed loop system with heat exchanger in mild climate

116 Patterson, John, Solar Hot Water Basics

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• 50/50 water/propylene glycol – closed loop system with heat exchanger in extreme environment (below freezing).

• Heat exchanger – in closed-loop systems, a series of tubes, plates, or other metal channels that allow transfer of heat from HTF to water without mixing. The type and size of exchanger will influence efficiency significantly.

• Pump – in active systems, used to circulate water or HTF between collector and storage tank (not required in batch or thermosyphon systems).

• Expansion tank – required in a closed-loop system where the operating pressure of the system is fixed and HTF volume will vary based on temperature. The expansion tank is sized according to the amount of fluid in the system – see manufacturer’s specifications.

• Control box – this circulates HTF via the pump in an active system whenever the collector temperature is higher than the storage temperature. DC systems are simpler in operation; the pump is PV powered and thus circulates fluid when there is sufficient solar energy produced to power the DC pump.

• Isolation valves – manual valves on incoming and outgoing lines to the (backup) solar collector and tank, to isolate the solar tank in case of a problem and allow continuous operation of the main geyser. These should also be installed when the collector is the main energy source to allow easier maintenance or removal.

• Backup water heater – natural gas, propane, electric, or wood water heater used when solar hot water system does not produce a typical 49°C thermostat setting. A tankless water heater is the most efficient system and is appropriate for use in remote lodges, unless a wood fired boiler is an option. For more on this topic see the relevant sections below.

• Tempering valve – also called thermostatic mixing valve, installed to prevent scalding (e.g. >70°C), this adjustable valve is the last component in the system and opens to mix cold water with the hot water stream.

Collector temperatures vary according to sun, collector type, and ambient temperature. The following guideline can be used as a rule of thumb117:

Ambient Conditions Temperature sunny and warm 60°C-80°C sunny and cold 50°C-65°C

cloudy and warm 20°C-30°C cloudy and cold 10°C-15°C

117 Patterson, John, Solar Hot Water Basics

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Tankless water heater

Tankless water heaters, also called instantaneous or on-demand water heaters, heat the water stream as it flows, and they are typically electric or propane fueled, although oil/kerosene models are available that can be modified to run on biodiesel. Water enters the unit and is heated in a series of burners or electric coils; unlike a storage tank delivery system, where temperature is independent of flow rate, a tankless heater is rated to add a specific temperature increase at a given rate of flow. Thus, final output temperature is dependent on the on the heater rating, the temperature of the input water, and on the actual flow (Note that some models are not designed to handle preheated water). Tankless heaters have the advantage that there are fewer ‘standby losses’ compared to a water tank, where much heat can be lost through the tank insulation or by conduction out the walls of the piping in water transmission.

Tankless water heaters will not fit every application, however:

• Gas availability and transport is difficult in Africa. • Electric units will require a large generator or mains electricity. • Gas units with pilot light require stand-by electricity to function. • Water pressure must be at least 2 bar (20 meters head) for good operation. • Minimum activation flow is typically 2-3 liters per minute. • May have maintenance problems in areas with water high in mineral content. • Some have long delay between startup and hot water delivery, i.e. 5 seconds.

Tankless water heaters operate in this sequence118

1. A hot water tap is turned on and cold water enters the heater.

:

2. A sensor detects the water flow and heater controls automatically activate the burner or heating element.

3. Water circulates through the heat exchanger and is heated to the designated temperature. 4. When the tap is turned off, the unit shuts down.

Gas fired tankless water heaters have the following characteristics119

• Requires venting, and typically should be located outside.

:

• Power-vented units require external electrical source for blower and electronics. • Larger standby losses in heat escaping with flue gas. • Units with pilot light will burn excessive gas, however piezo-electric, electronic ignition, and

hydro-electric turbine-powered igniter options are available. • Can heat more water than an electrical unit.

Electric tankless water heaters are described below:

• Require no venting, and can be located anywhere. • Not as powerful as gas fired units, so may not work in cold climate without preheated water.

118 Puffer, Homepower #118, pg. 74-79. 119 Puffer, Homepower #118, pg. 74-79.

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Photo 69 Propane tankless heater on the Shire River, Malawi.

Photo 70 Many electric geysers have location for electric element as well as inputs for other hot water sources.

Electric

Most hot water heaters (called geysers in UK and many African countries) are electric. They are very efficient in the conversion of electrical energy into heat, however the conversion of energy to electricity, whether sunlight or petrol/diesel, and transmission of that electricity to the unit, will be very inefficient. An electric geyser can be used as a storage tank for some solar or wood fired hot water heaters, however, with the electric element serving as a backup for periods of heavy use and/or cloudy conditions.

Wood fired boiler

Traditionally known in the African safari industry as ‘donkey boilers’, 'Tanganyika boilers', or ‘Rhodesian boilers,’ these are simple masonry constructions which hold a water tank or double tank system over a firebox. Donkey boilers are cheap and easy to construct, but they are incredibly inefficient. Donkey boilers can be single or double tank, and they can be arranged horizontally or vertically in orientation. Unfortunately, there is almost no published data on donkey boilers, and existing designs appear to be based only on tradition and copied designs, so unfortunately there is not much development of higher quality systems that produce heat more efficiently.

The most efficient boiler types employ gasification to burn secondary gases created in the combustion process (see below). Usually these units will employ a fan to blow preheated air into a second combustion chamber, where the oxygen ignites these other super heated gases. This additional energy release is also captured by the surrounding water jacket for more efficient water heating.

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Photo 71 Advanced wood fired boiler, Nairobi.

Photo 72 Typical simple wood fired boiler from 200l barrel, South Luangwa National Park, Zambia.

In a single tank system, the firebox sits below the storage tank, and water is drawn from the top and enters in the bottom. These systems are simple but can have issues with pressure and heat stratification in the tank. Double tank systems have one tank above the fire box for heating, and another tank above for delivery of hot water. The hot water travels to the upper tank by convection. Any donkey boiler system will have a pressure relief valve to prevent steam explosion, and this is typically an elevated galvanized iron pipe vent, although a standard pressure relief valve will work just as well.

More modern systems, called outdoor boilers in the U.S., are constructed with the firebox surrounded by a ‘water jacket’ firebox design that is a vast improvement over the standard arrangement of storage tank over the firebox. Outdoor boilers are premanufactured and have lower emissions, but still are known to have durability and quality issues, and they are subject to intense regulation in North America due to particulate emissions and stringent air quality standards. Note that all wood fired boilers are inefficient because the water being heated effectively lowers the temperature of complete wood combustion (i.e. 70C water lowers the wood combustion temperature well below that necessary for complete combustion of all flue gases, see below.)

‘Jacketed’ design can be accomplished with a standard donkey boiler, but it will require a higher level of technical skill and required tools (such as jig saw, grinder, 1/2" drill, arc welder) to fabricate. The cost will also be considerably higher with such units, and unfortunately, again there is no published information on this or established public domain designs.

The following recommendations are made for using wood as a combustion resource120

• Size the boiler according to the intended load or use.

:

• Start the fire such that it ignites quickly and builds to full intensity without smoldering. Research suggests that up to one-half of the total emissions for an individual burn cycle (for non-catalytic stoves) occur during the start phase121

120 Guide to Residential Wood Heating, pgs. 56-60.; US EPA Burnwise Tips

.

121 Houck, pg. 4.

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• Wood fires burn best in cycles of 3 to 8 hours, starting with the ignition of a new load and ending when that load is reduced to a coal bed. Do not let the fire smolder overnight.

• Remove ash between each cycle, and clean the exhaust stack regularly.

• Use a thermometer on the exhaust stack to monitor combustion temperature.

• All firewood should be split, securely covered or stored, and aged at least six months.

• Use small pieces of firewood arranged loosely in a cross pattern to burn quickly.

Wood undergoes the following stages in combustion122

1. Stage One Combustion - the wood is heated to evaporate moisture, <280°C.

:

• Wood is heated to a certain depth. • Water in the wood boils and evaporates as it approaches 100°C. • This evaporation (phase change from liquid to gas) requires considerable energy, so until all

water is evaporated, no additional heating of the wood occurs. • No appreciable heat transfer to furnace, stove, or water tank occurs. • Between 100°C and 260°C, the major gases abundant in creosote are produced: carbon

dioxide, carbon monoxide, and acetic and formic acids. • These gases are generated but do not ignite so long as there is moisture remaining

undergoing the phase change. • The wood starts to break down chemically at 260°C, and volatile matter is vaporized,

containing between 50 and 60% of the heat value of the wood. 2. Stage Two Combustion – wood temperature >280°C: the heat producing stage.

• Primary Combustion – wood combustion at 280°C to 480°C o releases large amounts of unburned combustible gases, called Secondary Gases,

including methane and methanol as well as more acid, water vapor and carbon dioxides. o These gases contain up to 60% of the heat content of the wood.

• Secondary Combustion – secondary gases burn at >600°C o additional oxygen is require to burn these secondary gases (primary combustion

consumes all oxygen in the vicinity of the wood) o air supply is critical, as too little will not allow full combustion, and too much will cool the

wood <600°C. o Some stove designs promote secondary combustion through a catalytic combustor,

circulation of gases in the stove, baffles and massive stove construction to hold heat. o This design has not been developed with boilers, as the water being heated has a

cooling effect on combustion gases. 3. Stage Three Combustion – Charcoal burning at temperatures over 600°C.

• Charcoal - carbon chains of cellulose and lignin molecules remain following combustion of volatile gases,

• Long duration burn, with a low rate of heat output

122 Vogel, pg. F-1.

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ELECTRICAL SYSTEM

Before proceeding with electrical system design, a thorough research of the site, the exact needs of the lodge, and the national and regional economy should be undertaken. This will determine the amount and seasonal availability of solar or wind energy, exactly what level of service is to be provided to the client at the facility, and the local and regional availability of parts, tools, skilled labor, and fuel. Seemingly small decisions such as the inclusion of hairdryers or hot-pots in rooms can have considerable impact on system sizing and cost; likewise, an underestimation of the transport cost or availability of fuel can quickly make a large generator set uneconomical despite lower installation cost. Likewise, the cost of armored cable can often control the budget for a centralized versus individual cottage PV system.

Considerations for electrical system planning:

• Initial installation costs • Operational costs amortized over term of the concession • Availability of skilled electricians for installation and maintenance • Availability of tools, materials, parts, and fuel\ • Cost of transporting and storing fuel in addition to unit costs of fuel • Backup system type and costs • Possibility to expand system over time • Cost of armored cable

Two basic concepts for the electrical system are available to the lodge designer: storage and non-storage systems. A storage system would incorporate batteries with electrical charging by photovoltaic panels, a wind turbine, microhydro power, and/or a generator. Non-storage systems include generator and mains power supplied by a utility (for the purpose of this document, mains power solutions are considered to be commonly available technology and will not be discussed). In this case, power is on demand, but no batteries allow for capturing excess generation or providing power when the generator is off. A system optimized for cost will probably include a generator for max loads or compensation during periods of low sunlight, wind, or flow, at least until the cost of these alternative energy systems become significantly lower. Ultimately, though, the batteries will be the largest cost over the lifetime of a system, so their selection and use should be very carefully performed.

Calculating load

Loads for the two approaches are calculated very differently due to the fundamental nature of the power supply: a generator is full power when on, and no power when off, whereas a battery bank has a defined capacity, which can only be recharged slowly and should not be fully discharged, so as to prolong battery life. Thus, generator sizing is a ‘worst case scenario’ calculation, with all loads totaled, including all start up loads, which can be double the operation load for appliances such as freezers, refrigerators, pumps, and motors. Additionally, a generator should have allowance for altitude as well as operational load lower than 100% (75% operation load is typical). A battery array, on the other hand, is calculated by summing all loads multiplied by their usage per day, and then multiplying this total by a number of days for which the array should be operational without recharge (due to lack of sun, etc.).

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Photo 73 High efficiency vehicle type 12v refrigerator, Livingstonia, Malawi.

Photo 74 High efficiency Minus Forty 240v refrigerator, Majete Wildlife Refuge, Malawi.

Generator

Generator size in a typical system is determined by the total load in worst case scenario: all pumps, refrigerators, and cooking appliance in use or coming online at the same time. In other applications, the generator is only one component of a larger system, using batteries, and the size need not cover the worst case scenario. In some cases, a PV system may use a generator for the short time that a large refrigeration unit or units come online, and then it will shut off when the device is running.

Photo 75 New sound attenuated (78db) Lister-Pack 4.5kW generator, Davis & Shirtliff showroom, Nairobi.

Photo 76 Supersilent sound attenuated (51db) 6.5kW Honda Generator.

Types of generators:

• Diesel / Petrol • Sound attenuated (shrouded) • Fuel injected / carbureted

• AC + DC • Single phase / Three phase

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Petrol as a fuel has the following advantages and disadvantages:

Advantages: • Easily serviceable • Readily available • Cheaper • Typical for portable generators

Disadvantages: • Highly flammable • Will eventually deteriorate • Fuel storage

Diesel has the following advantages and disadvantages:

Advantages: • More durable • More fuel efficient

Disadvantages: • More expensive • Dirtier and produces more emissions

Other features to look for in a generator123

• Electric start with two-wire remote start capability, meaning all starting control functions (such as cranking and crank duration) are handled within the generator, not externally.

:

• Liquid cooling: quieter and longer life • Onboard starting battery charging • Low engine speed ~ 1,800 rpm: quieter, less vibration, lower fuel consumption, longer life, less

maintenance. • No or minimal standby load, to eliminate draw on a PV system • Sound attenuated + residential muffler. • Floating or unbonded neutral-to-chassis connection, to reduce shock hazard.

A generator should be located using the following criteria:

• Should be installed outdoors, under a roof, or in a room with good ventilation. • Should not over heat, so any installation should be well ventilated and as cool as possible. Some

generator manufacturers can provide special thermostat/coolant valves for external radiators or coolant tanks.

• Minimum 1m on each side for servicing. • Position as close to the distribution board/load as possible to reduce armored cable costs. • Place far enough from guests so that operation is not noticeable.

Typically, a generator only system uses the following design procedure:

• Determine total electrical load connected – worst case scenario • Calculate voltage, frequency, and phase • Include any special requirements • Decide whether automatically started • Determine acceptable sound emissions

Generators can be sourced in 230v single phase and 400v three-phase power production. An average home uses a generator between the sizes of 5 kVA and 40 kVA124

123 Homepower #131, pg 97.

, but the level of service at a tourist facility can vary from 0 to 100+kVa, depending on the level of service. Typically, a smaller facility can

124 Bundu Power

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operate with single phase electricity, whereas a larger facility is more efficient with three phases. ‘Larger,’ in this context, means both geographic footprint as well as total electrical load, as a three-phase system can transmit more power further with smaller cabling, which will reduce both installation and operating costs. However, a three-phase system is more complex to design, install, and maintain.

A stand-alone generator system is sized according to the following procedure:

Loads / Power Factor / Altitude / Temperature • surge rating / load % = generator size

1. Calculate all loads in system including startup loads for refrigerators – assume all appliances are on at the same time and all compressors are in startup mode.

2. Divide by .85 for power factor 3. Decrease efficiency for altitude (see manufacturer for details, or use 1% per 100m) 4. Decrease efficiency for heat (see manufacturer for details, or use 1% per 4°C over rated

temperature). 5. Multiply by 1.2 for surges 6. Divide by .75 to assume operation at 75% for durability, fuel economy, and unexpected loads 7. Decrease efficiency for poor fuel (contact generator importer)

A generator plays a major role in photovoltaic systems, and should be considered early in the design as an integral component125

• Backup charging is possible to compensate for any problems with a PV or wind turbine system, or to provide power in system with ‘one-day autonomy’.

:

• Battery equalizing in flooded batteries, which need to be overcharged several times each year. • Can run loads that exceed the inverter capacity, such as pumps, refrigerators, icemakers, or air

conditioners, or can compensate for an underdesigned PV system that will be expanded later to include refrigeration or water pumping.

When sizing a generator for a PV system, a procedure working back from the battery bank is used126

1. Calculate loads, PV array size, and battery bank according to normal PV procedures, and calculate total Amp-hours of the battery bank

:

2. Divide by ideal charge rate, C/10, to determine Amperage of inverter (i.e. 800 Ah / 10 = 80 Amps). 3. Check that this inverter rating + PV amperage rating are not greater than the batteries’ maximum

charge rate. 4. Select a charger/inverter for the battery charging application (i.e. Xantrex XW4548). 5. Check manufacturer’s specifications for AC input charging current necessary to create the full

charge rate (24.8A • 240 V = 5,950 W) 6. Use this wattage to input into stand-alone generator system sizing, Step 2. Note that if additional

loads will be run while charging batteries, they should be now included in the total.

Note that when a generator is located on site, a fuel storage facility will also be necessary (and will probably be necessary even for company vehicles if no generator is present). A fuel storage facility should be a dedicated room or area with fireproofed walls and ceiling and spill mitigation measures.

125 Homepower #131, pg 96 126 Homepower #131, pg 99

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Photovoltaics

A photovoltaic (PV) system is a major design and maintenance component of a remote ecolodge, but with available sunlight and the irregular supply of petroleum in many African countries, these systems are becoming both cheaper and more reliable than traditional generator systems. Furthermore, PV components and skills are becoming more ubiquitous and cost competitive every year, whereas the same cannot be said of petroleum products or even mains electricity.

Photo 77 Outback Power inverter in 240v microgrid under construction, Nkhotakota Wildlife Reserve, Malawi.

Photo 78 Battery array for 3000w microgrid, Malawi.

Available photovoltaic power is not as clear to define as wind or hydropower, due to the numerous components involved, the efficiency to the PV module, and the vagaries of the site. It can be represented by the following equation:

PV Power = ~1000 w/m2 • module size (m2

PV system design takes a different approach from that of a generator system. Several methods are possible, and many worksheets can be found on manufacturer or dealer websites. The following approach combines the recommendations from

) - tilt - shade - temperature effects - inverter

Stand-alone Solar Electric Systems by Mark Hankins and ‘Six Steps to Sizing a PV System’ by Steven Shepard127

1. Calculate all loads and number of hours per day. If an appliance is rated in amps, multiply amps by operating voltage (240V) to determine watts.

:

a. Calculate AC loads b. Calculate DC loads c. Select system voltage

2. Optimize power demands - examine power consumption and reduce needs as much as possible. Replace incandescent lamps with compact florescent and/or LED.

3. Recalculate loads in Step 1. 4. Size and select battery array.

a. Enter your daily amp-hour requirement from Step 3.

127 Hankins, 118.

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b. Enter the maximum number of consecutive cloudy days expected, or the desired number of days of autonomy for the system.

c. Multiply the amp-hour requirement by the number of days for total amp hours required. d. Enter the depth of discharge – should not exceed 80%, but follow manufacturer’s

recommendations. e. Divide the amp-hours of storage needed by the depth of discharge. f. Ignore cold weather effects for most locations; contact battery manufacturer if site is in a cold

weather region. g. Divide the total battery capacity by the battery amp-hour rating and round off to the next

highest number. This is the number of batteries wired in parallel required. h. Divide the nominal system voltage (12, 24 or 48V) by the battery voltage and round off to the

next highest number. This is the number of batteries wired in series. i. Multiply the number of batteries in parallel by the number of batteries in series. This is the

number of batteries required. 5. Determine solar insolation at the site.

a. Multiply daily amp-hour requirement x 1.2 (to compensate for battery inefficiencies) to find array amp hour requirements.

b. Calculate total solar array amps required by dividing array amp hour requirements by average sun hours per day at lodge site

c. Divide solar array amps required by optimum or peak amps of solar module (see module specifications) to find total number of solar modules in parallel.

d. Multiply parallel modules by 2 for 24V system or 4 for 48V system for total modules required. 6. Size and select inverter, inverter/charger, and charge controller128

a. Inverters may have additional capabilities including battery chargers, AC transfer switches, metering, load and generator control outputs, data logging, and networking connectivity.

b. Modified square wave inverters (also called modified sine wave) are cheaper but pure sine wave inverters must be used for electronics, pumps, compressors, and refrigeration equipment.

c. Battery charger and AC transfer switch to charge the battery and/or run AC loads with a backup generator when battery power is low. (Also facilitates battery equalization).

7. Design main circuits a. Cables b. Fuses c. Switches

Load calculation is done by deriving the loads for various appliances from tables or from the manufacturer, then multiplying each times the predicted hours per day of use. Obviously, this is not a precise method, so some items should be sized conservatively.

System voltage is the level at which the batteries, charge controller and solar array will operate. 12V and 24V are most common, but some systems will operate at 48V to save costs on cables. A higher voltage will reduce transmission losses in the circuit, but most DC appliances, lights, and pumps are specified at 12V. MPPT charge controllers can operate on any voltage from 15V to 100V+, and then 128 Freitas, Homepower #134, pg.88-94.

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deliver this to the battery array at 12V or 24V. Most charge controllers operate at either 12V or 24V129

Battery voltage selection

. The system voltage can be divided, for example the solar array and batteries can be located near the kitchen to run refrigerators and freezers at 12V or 24V, and an inverter charger can then take current to distant cottages at 230V for lighting and outlets.

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• 12V – simplest and cheapest, and the best option for individual units in cottages or refrigerators/freezers. Can be coupled with an AC inverter to allow 230V use.

:

• 24V – better option for 1000W+ PV modules, PV modules over 30m from power station, or wind/microhydro over 100m from power station

• 48V – best for locations where power station is up to 120m from PV modules or wind/microhydro is up to 300m away.

• Consult a PV installer for best application of 24V vs. 48V.

Wind

Wind turbines are typically more expensive than PV arrays, and they are limited to select areas such as coastlines, mountains, or unique topographies that receive sufficient wind. However, in some cases wind turbine can provide a good complement to a PV system where windy conditions accompany cloudy weather and the PV system underperforms. Wind velocity increases with height above ground, so the cost and complexity of the tower is often the determining factor in system design.

Photo 79 Wind turbine on Nchisi Mountain, Malawi.

Photo 80 Wind turbine on Lamu Island, Kenya.

Available wind power is determined by the following equation:

Wind Power = Turbine Efficiency (~40%) • ½ • Air Density (kg/m3) • Wind Speed (m/s)3 • Swept

Area (m)2

Due to the change in air density with increased altitude, the system will produce about 1% less power for every 100m above sea level.

= Watts

129 Hankins, 120 130 Backwoods Solar.

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The following procedure can be used to size a wind turbine system131

1. Determine kWh demand as per PV system sizing.

:

2. Determine tower height estimating the future height of any trees on site. a. 10m minimum clearance between bottom of rotor and top of nearest obstacle within 150m b. A higher turbine will always produce more power, meaning that often a smaller turbine on a

taller tower is more efficient c. A higher turbine endures less turbulence, meaning less wear and maintenance

3. Estimate the available wind resource, both through published information and by long term measurements at the site using an anemometer.

4. Determine rotor diameter, based on predicted kWh at predicted wind speed. Wind Output Calculator software, such as WindCAD, can assist with this calculation.

5. Compare available wind turbine products at the desired rotor diameter using the manufacturer’s turbine energy-output charts, and select a product. Purchase a larger unit than necessary if predicted loads will increase over time.

6. Select BOS (Balance of System) components, including the inverter, battery array, additional sources such as generator or PV array, and cable sizing.

Microhydro

Hydropower is a unique system in that it can often deliver both energy and drinking water to a site. It is limited to mountainous areas, and unlike PV and wind systems, hydropower installations are often limited in how much power they can produce based on available water head and flow. Additionally, many mountainous water courses in Africa are seasonal, and available water may already have a dedicated use in downstream communities. However, for the some remote locations it will be ideal, and many countries in Africa (including Rwanda, Mozambique, and Malawi) are recognized as locations of tremendous unrecognized hydropower potential. Microhydro will be defined here as a hydropower installation under 5 kW.

Available water power is determined by the following equation:

Water Power = Turbine Efficiency (~40%) • Head (m) • Flow (kg/s) • Gravity (m/s2

For example, a stream 27 meters above the turbine outlet, flowing at 8 liters per second, would produce 27m •8 l/s • 9.81m/s

) = Watts

2 ≈ 2.1kW. Note that frictional losses are ignored and l/s is converted to kg/s for calculating power, as 1 liter water = 1 kg. Microhydropower DC generators are manufactured from 100 to 3000 Watts, but should not be considered at sites with less than 10m head132

Microhydro systems are typically very good for battery life, because energy supply is rather constant and batteries do not stay in a reduced state of charge for long. This also allows for a smaller battery bank

. AC units are made between 300 Watts and 5kW.

133

Hydropower installations are comprised of the following elements:

. For these reasons, the cost of a microhydro installation may be offset by reduced battery replacement costs; however the total operating costs of the system will be harder to predict.

131 Homepower #137, pg. 47. 132 Stapleton, Microhydro Systems, 4.9 133 Cunningham, Homepower #117, pg. 43.

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• Existing river or stream • Diversion with screen and inlet • Penstock – piping from inlet to turbine • Turbine including housing, nozzles, and generator • Transmission lines, typically to a larger PV/Wind/Hybrid type system • Dummy load, such as a heating element, to receive power when no other load is present and/or

batteries are fully charged.

The following hydro installation design procedure is followed134

1. Determine the static pressure head available to the system: elevation of source minus elevation of turbine outlet.

:

a. GPS is adequate for preliminary investigations. b. For final sizing of the turbine more precise surveying instruments should be used: a laser

level, a surveyor’s transit, a builder’s level on a tripod, or an Abney level. c. For short systems a garden hose with a pressure gauge is sufficient.

2. Determine the available flow in liters per second (l/s). a. Container fill method for small streams: find a location where the stream can be diverted into

a bucket or barrel of known volume, and measure the time required to fill the vessel. Multiply these figures to get a flow number in l/s.

b. Weir method for accuracy in small and medium sized streams – construct a permanent or temporary dam with a rectangular slot, and measure the flow through this slot with a reference point up stream. The difference in height can be measured and a weir table used to calculate the flow.

c. Float method for large streams: Find a section of stream 3m long with consistent channel dimension, and measure the width of the channel and depth at .3m intervals. Average these depths and multiply times the channel width for cross sectional area. Time a floating ball through this 3m section, and multiply that figure (in m/s) times the calculated cross sectional area to find the flow in m3

3. Determine pipe distance and losses. /s. Divided by 1000 for l/s.

a. Measure horizontal distance of penstock and b. Determine pipe type based on vertical pressure c. Determine pipe diameter based on available flow d. Calculate frictional losses based on type of pipe and flow as with gravity feed water supply

system 4. Calculate effective dynamic head by subtracting frictional losses from total pressure head. 5. Size nozzle

a. Water velocity must be below 1.5 m/s. b. Maximize flow while maintaining water in system c. Systems can have multiple nozzles

The first element in the microhydro plant is the diversion. This is a dam, collection box, pond, or other natural or manufactured structure that allows water to cover the intake while restraining fish, animals, air

134 New, Homepower #104, pg. 43.

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bubbles, and any debris large enough to clog the nozzles from entering the intake. In systems with high head pressure, fine particles should also be removed as they will wear the impeller blades on the turbine.

Types of diversions135

• Pipe with screen – can be prefabricated or homemade; requires frequent cleaning.

:

• In-line canister filter – a manufactured ‘y-junction’ type filter that is effective but must have a pre-screen upstream or it will clog too quickly.

• Flume with screen and settling chamber – a pipe diverts water to a screen and then into a plastic or steel vessel with an outlet to the turbine and a return outlet back to the stream; fine particles settle at the bottom of the tank and must be removed on a regular interval through a cleanout valve at the bottom.

• Screen box on the side of a dam with multiple screens to filter intake water • Pond bucket – a floating or fixed bucket with holes drilled to filter water; inexpensive solution for

stable locations but does not filter floating debris well. • Culvert tap – a hole is drilled or cut into the bottom of an existing culvert, and a short lip is welded to

the end of the culvert to create a small ponding area. Note that this will decrease the hydraulic capacity of the culvert.

• Spillway with Coanda-effect screen – a spillway on a weir with a specially designed shear screen, which intakes water while debris washes over.

• Slow water zone diversion – a small pond is constructed near a slow moving river, and an intake is placed in this pond. Gabions can be used to create a zone of slow water to increase sedimentation if the main river velocity is too high.

The penstock is the water delivery piping, and it should be rated such that it can withstand the pressure of the system, but note that lighter duty pipe can be installed near the diversion, and heavier pipe specified as necessary closer to the turbine. The minimum quality should be Grade 6 (also called ‘Class B’), which can withstand 6 bar or 60m water head. It can be of five types:

• PVC – Polyvinyl Chloride is lowest in cost, and it is typically lower quality; comes in 6m sections which must be prepared and glued. This can be time consuming on long piping runs.

• uPVC – unplasticized PVC or rigid PVC, sometimes mistaken to have rating for exposed use in ultraviolet light.

• HDPE – High Density Poly Ethylene is more expensive than PVC. It is sold in 100m rolls and is flexible, thus it will better fit varying contours (it can be bent to radius 15x Outside Diameter (O.D.) though 25x O.D. is recommended136

• PPR – Polypropylene Random Copolymer, a new pipe type available in eastern Africa, for higher pressures. Marketed as an alternative to GI pipe.

). It is connected by couplings or butt welds, and is common in southern Africa.

• GI pipe – Galvanized Iron – traditional material, but relatively expensive and a rough interior creates higher friction losses in the system.

135 Homepower #124, pgs 70-71. 136 Doshi Enterprise Ltd, Nairobi, Polyethylene Pipes Systems Catalog.

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Turbines can be of two types137

• Impulse turbines route water through nozzles at a wheel (i.e. Pelton and Turgo wheels). These are for higher head applications.

:

• Reaction turbines are typically centrifugal pumps used as turbines, where the impeller is submerged.

Low head applications

Submersible Generators produce electricity due to the flow of water in a stream or river. They originate in the sailing industry, where they can produce up to about 100W, depending on flow. Due to the cost, low output, and other options, these are not recommended unless no other option is available. In this case, a diversion channel to a protected generator housing should be constructed to allow regular flow without debris. Example products include the Aquair by Ampair. Low head high flow generators can produce more power, up to about 1500W. Example products include the LH 1000 and the Turgo Stream Engine by Energy Systems and Design.

Hybrid System

A hybrid system has more than one power source. For ecolodge applications, this will typically mean a PV, Wind, or PV/Wind system with a backup generator. In these systems, the generator will either be a supplement to the PV system to assist battery recharging or it will be included to handle peak loads or for dedicated loads (such as freezers or icemakers). For these ‘marginal’ uses outside of the normal demand, a generator is usually cheaper, and the advantages of a generator become greater with system size. And although a generator will require significant maintenance and fuel, in an emergency it is a dependable backup. The controls and wiring for a hybrid system are more complex in hybrid systems, and an experienced engineer or electrician should be employed to design a complete system.

Advantages of a hybrid system138

• More economical than PV to achieve the ‘final 5%’ of design load, or to achieve 3-5 day autonomy.

:

• Lower initial cost than PV for a system of similar size. • Increased reliability for two independent electrical systems. • Design flexibility, in that the PV system can increase in size over time and the generator use for

battery charging reduced. • Battery bank can be smaller if charging is available on demand from generator.

137 Cunningham, Homepower #117, pg. 42. 138 Sandia Laboratories

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Photo 81 Hybrid solar and wood fired hot water system, Nkhotakota Wildlife Reserve, Malawi.

Photo 82 Hybrid PV and wind turbine borehole pumping scheme, Northern Malawi.

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GLOSSARY

AC – alternating current, which cycles in Africa at 240V and 50 Hz

Aeration – addition of air to a wastewater body to facilitated aerobic digestion, either by spraying water or diffusing air through the water in bubbles. Aeration can also be used in water treatment to convert Fe to FeO2

Aggregate – inert material such as crushed rock, gravel, or expanded mineral that is added to cement, sand, and water to produce concrete. Aggregate quality is very important to final concrete strength: it should be hard, dense, angular, and clean.

and precipitate out the iron taste of water.

aH – ampere hour, unit total charge commonly used to describe battery capacity, whereby 1 amp-hour is a capacity of one amp available for one hour.

Anaerobic digestion – bacterial digestion of wastes in the absence of oxygen, as in a biogas reactor or septic tank.

Ancillary Development – Additional development related to a particular project, particularly referring to services which supply it.

Anemometer – tool to measure average and peak wind speed, and may also measure wind direction, energy density, and wind distribution.

Aquifer – a rock or sediment formation underground that sufficiently permeable to allow an economic extraction of water through a borehole or spring

Backfill – earth filled around a foundation to replace earth removed for construction.

Bar - a unit of pressure equal to 100kPa, 10.19m head, or 14.5psi.

Baseline Studies – Studies of existing environmental, economic, or social conditions which are designed to establish the standard against which any future changes can be measured or predicted.

Benchmark – A process through which an organization compares its internal performance to external standards of excellence, and then acts to close whatever gap exists or capitalizes on its leadership position. The objective of benchmarking is to achieve and sustain best-in-class performance through continual improvement activities.

Best Practice – When a company uses the best available technologies and techniques known to their industry, in this case to achieve sustainable tourism.

Biogas – a mixture of ± 55% methane / 45% CO2

Black Water – water from toilets that must be treated before reuse or release to environment.

produced by anaerobic digestion of wastes by bacteria in a biogas reactor. Some Hydrogen Sulfide (HS2) will be present, and it should be reduced with a steel wool fiber filter to reduce pitting and corrosion in any engines which run on th

Boiler – a closed vessel used to produce hot water or steam.

Booster Pump - A pump used to increase pressure in a water system.

Borehole – common name in Africa for a drilled well. Typically 110mm for a hand operated pump and 125mm for an electric submersible pump, and over 20m in depth

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Building code – A set of ordinances or regulations and associated standards intended ensure quality by controlling aspects of the design, construction, materials, alteration, and occupancy of structures necessary to ensure human safety and welfare, including resistance to collapse, damage, and fire.

Cable Splice – a splice in electrical cable for submersible pumps available in kit form. Typically called ‘Metaplast.’

CAD – Computer Aided Design. AutoCAD, Microstation, Visio, and Vectorworks are common software for CAD work. CAD can assist in building layout and quantity surveying, but it does not replace professional architectural skills.

Carrying Capacity – An imprecise term which can mean a number of different things in different contexts. It can refer to the population of humans or animals which can be supported by a given environment. Alternatively, it could refer to the capacity of the environment to tolerate stress or pollution.

Casing - Plastic or steel tube that is permanently inserted in the well after drilling. Its size is specified according to its inside diameter. Typical sizes are 125mm (5”) and 150mm (6”).

Cast-in-place concrete – concrete members formed and poured on the building site in the final location where they are needed.

CBO - Community-Based Organization, whose principal concern is the welfare and development of a particular community. A CBO may not represent all the households or interests in a particular area.

Cellular repeater – a system used to boost mobile phone reception with a reception antenna, a signal amplifier, and an internal rebroadcast antenna. Can be combined with laptop modems to provide internet access in remote areas.

Cement – a powder with adhesive and cohesive properties that sets into a hard, solid mass when mixed with water.

Centrifugal pump - A pumping mechanism that increases the available energy and pressure in water by means of an "impeller".

Cesspool – a covered excavation in the ground that receives sewage and which is designed to retain organic materials and solids while allowing liquids to seep into soil.

Charge controller – a solid state device that protects the batteries, the loads, and solar array from high and low voltage fluctuations and may perform other maintenance or management functions in the system

Check valve - valve that allows water to flow in only one direction.

Chlorination – the addition of chlorine to filtered water to both kill bacteria immediately and throughout the distribution system

Circuit breaker – an electric device used to open and close a circuit by non-automatic means or to open a circuit by automatic means at a set overcurrent without damage.

Clay – a very cohesive soil type made of microscopic particles less than .002mm

CMU – Concrete Masonry Unit produced in a mould with a cement : sand mixture, usually at 1 : 6. Typically hollow.

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Community participation – the engagement of affected populations in the project cycle, including assessment, planning, design, implementation, operation.

Compaction (compression) – densification of soil by a mechanical means to expel air and reduce voids for increased load bearing or durability.

Composting – process by which an organic material undergoes an aerobic biological degradation to a stable end-product.

Compressed earth block – a dense soil block made by a mechanic device with human or hydraulic power which can be mass produced as a standardized masonry unit. Can be stabilized or unstabilized.

Concrete – a mixture of Portland cement, sand, aggregate, and water that has structural properties when cured, and can be used for foundations, columns, beams, and floors.

Conduit – a steel or plastic tube through which electrical wires are carried.

Confined masonry - Confined masonry construction consists of unreinforced masonry walls confined with reinforced concrete tie-columns and reinforced concrete tie-beams. The masonry walls carry seismic loads and concrete is used to confine the walls. This is in contrast to reinforced concrete frame buildings with infilled masonry, where the concrete frames carry the load.

Consolidation – the process of compacting freshly placed concrete in a form, typically performed by manual rodding or with a powered vibrator.

Construction documents – all the written, graphic, and pictorial documents to describe the design, location, and physical characteristics of the elements of the project necessary to obtain a building permit.

Convection – the process of heat transfer from one location to another by movement of liquid or gas. A material will expand when heated and lighten, causing it to rise and become displaced by a denser, colder material.

Conversion efficiency – efficiency of the inverter to convert power to 230V, typically 70% to 96%.

Creep – permanent deformation of a material (typically concrete) when subjected to a constant stress.

Critical Path – sequence of schedule activities that determines the duration of a project.

Curing – protecting concrete after pouring by maintaining temperature and moisture content of the mix, typically by splashing water and covering with plastic sheeting.

DC – direct current, which flows in one direction. This is the electricity generated by solar panels, and can be used to power lights, refrigerators, and some freezers. It is usually implemented in 12v, 24v, or 48v systems

DC Motor, brushless - High-technology motor used in centrifugal-type DC submersible pumps. The motor is filled with oil, and an electronic system is used to precisely alternate the current, causing the motor to spin.

DC Motor, permanent magnet – used in DC solar pumps to allow a variable speed motor to operate at reduced voltage (in low sun) and produce proportionally reduced speed, causing no harm to the motor.

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Desalination – any of several processes that remove excess salt and other minerals from water. Reverse Osmosis is the technique commonly used for small scale desalination operations.

Design drawings – structural drawings prepared by the structural engineer that give all information needed for detailing and construction.

DoD – depth of discharge of a battery, meaning its percentage of total energy used during a cycle of use between charges.

Donkey boiler or Rhodesian boiler – a wood fired boiler consisting of a double walled tank or two-tank system whereby water can be cheaply heated and stored. Common in the safari industry.

Drop Pipe - The pipe in a borehole from the pump to the well head at the surface.

Ecosystem – A community of interdependent plants and animals together with the environment which they inhabit and with which they interact.

Ecotourism - environmentally responsible travel and visitation to natural areas in order to enjoy and appreciate nature (and any accompanying cultural features, both past and present) that promote conservation, have a low visitor impact, and provide for beneficially active socioeconomic involvement of local peoples.

Effluent – liquid discharged from a septic or other treatment tank.

EIA – Environmental Impact Assessment is an investigation of the possible positive or negative impact that a proposed project may have on the natural environment, undertaken as an integral part of planning and decision-making processes.

Environmental Statement – A document which sets out the assessment of the likely effects of the project on the environment.

Flocculation – the process of agglomerating colloid particles (i.e. fine clays) into groups by rapidly mixing a chemical such as Alum (Aluminum Sulfate) and then reducing agitation to allow settling.

Foot Valve - A check valve placed in the water source below a surface pump. It prevents water from flowing back down the pipe and losing prime, but it must be located within the Net Positive Suction Head. Typically sold with a wire mesh strainer.

Foundation – this is the lowest part of a building structure which transmits the loads of the building, occupants, and other loads to the soil without subsiding.

Friction loss - The loss of pressure head due to flow of water in pipe. This is determined by the pipe inside diameter, the flow rate, fittings in the pipe, and pipe length. It can be determined by friction loss charts or water modeling programs such as WaterCAD or EPANet.

Gabions – boxes from woven galvanized steel mesh which are filled with rock and can be used to control erosion, provide soil retention, build river fords, protect bridges and culverts, or provide foundation for structures. Shorter gabions are often called ‘Reno mattresses.’

Gate valve – used to isolate a section of pipe, but not to regulate or throttle flow, though for short periods it can perform this function.

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Genset - A generating set is a combination of engine, alternator, control system, and circuit breakers, typically mounted on a base. Often an integrated fuel tanks as well as sound attenuated canopies are included.

GIS – Geographic Information System for the input, editing, storage, retrieval, analysis, synthesis, and output of location-based (also called geographic or geo-referenced) information. GIS may refer to hardware, software, or data.

Governing system – in a wind turbine, actual wind speed over the design speed is compensated for by tilting the rotor up or to the side, or by controlling the pitch of the blade to increase drag and reduce rotation. Additionally, ‘stall regulated blade’ design allows the blade to perform less efficiently at higher speeds, reducing rotational velocity.

Gravity Flow - The use of gravity to produce pressure and water flow by locating the storage tank above the point of use.

Grey water – water from sinks, showers, baths, dishwashers, clothes washers, and other taps that can be reused for landscaping with only a minimum of purification, typically soap/oil skimming.

HDPE – high density polyethylene, a common plastic used for water pipes, membranes, and water tanks.

Head - pressure in water as defined in meters.

Hydrology – The study of the waters of the earth, especially with relation to the effects of precipitation and evaporation on water in streams, lakes, and on or below the land surface.

Idle power consumption - power used by the inverter with no loads, typically 10 to 50W, though some have ‘sleep’ modes.

Induction Motor (AC) - used in conventional AC water pumps, requires a high surge of current to start and a stable voltage supply, making it relatively expensive to run from by solar power.

Insolation – incident solar radiation, or the measure of solar energy in a given area over a specific period of time. The sun produces about 1350 watt-hours/m2

Inverter – a digital device which converts DC power to higher voltage AC power, with a typical loss of ±10%

.

Inverter / charger -

kVA – Kilovolt Ampere, is a measure of electrical load on a circuit or system. The kVA rating is limited by the maximum permissible current, and the kW rating by the power-handling capacity of the device.

kW – kilowatt, a measure of 1000 watts, which is a measurement of power. Related to kVA.

kWh – a kilowatt hour, determined by wattage over time. Used in PV calculations by multiplying device wattage times its (estimated) daily use. This is the common unit of sale for mains power.

Land use planning – The process to identify, evaluate, and decide on different options for the use of land areas, including consideration of long-term economic, social, and environmental objectives; the implications for different communities and interest groups; and the subsequent formulation and promulgation of plans that describe the permitted or acceptable uses.

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LCB - Linear Current Booster, an electronic device which varies the voltage and current of a PV array to match the needs of an array-direct pump, especially a positive displacement pump, allowing the pump to start and to run under low sun conditions without stalling or to pump more water at a given solar array output. Also called pump controller, an example of which is the Grundfos IO 100.

LED – Light Emitting Diode, a very efficient lighting device particularly suited to low cost solar electric systems

Life cycle assessment - also known as 'life cycle analysis', is the investigation and evaluation of the environmental impacts of a given product or service caused or necessitated by its existence, the goal of which is to choose the least burdensome option.

LVD – Low voltage disconnect, a charge controller feature which disconnects loads from the battery array when the voltage drops below a defined level (typically 12.3V / 40% State of Charge).

Mitigation – Any process, activity or design to avoid, reduce or remedy adverse environmental impacts likely to be caused by a development project.

Monitoring – ongoing review, evaluation and assessment to detect changes in the condition of the natural or cultural integrity of a place, with reference to a baseline condition.

MPPT – Maximum Power Point Tracker, a controller which optimizes the electrical output of a solar array by maintaining the voltage at which it is most efficient.

Net Positive Suction Head – also called suction lift, this is the vertical distance from the surface of the water in the source to a pump located above. This distance is to around 10m at sea level minus 1m per 500m altitude, and it should be minimized for best results.

Open discharge – The filling of a water tank that is not sealed to hold pressure.

Penstock – the pressurized line in a hydropower system that delivers water from a collection box to the turbine.

Percolation test – a method of testing absorption qualities of the soil, whereby a hole 100-200mm wide x 500-1000mm deep is filled with water and the time of seepage is measured to determine the percolation rate.

Perforations – Slits cut or holes drilled into the well casing to allow groundwater to enter; these may be located at more than one level at locations of water-bearing strata.

Physical planning – A design exercise based on a land use plan which is used to propose infrastructure for public services, transport, economic activities, recreation, and environmental protection for a settlement or area.

PPR – Poly-Propylene Random copolymer pipe.

Pressure - the amount of force per area in water that is created by a pump or gravity.

Pressure switch - an electrical switch actuated by the pressure in a tank. When the pressure drops to a low set-point (cut-in) it turns a pump on. At a high point (cut-out) it turns the pump off.

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Pressure tank – a fully enclosed tank with an air space inside. As water is forced in, the air compresses. The stored water may be released after the pump has stopped. Most pressure tanks contain a rubber bladder to capture the air.

Pressure tank precharge – the pressure of compressed air stored in a captive air pressure tank. A reading should be taken with an air pressure gauge with water pressure at zero. The air pressure is then adjusted to about 20kPa lower than the cut-in pressure. If set incorrectly, the tank will not work to full capacity, and the pump will cycle on and off more frequently.

Priming – the process of hand-filling the suction pipe / intake of a surface pump, necessary when a pump is located above the water source. A self-priming pump is able to draw some air suction in order to prime itself, but these are not as durable. Often necessary for centrifugal surface mounted pumps.

Pump controller – an electronic device that controls or process power to an array-direct pump. It may perform any of the following functions: stopping and starting the pump; protection from overload; power conversion; or power matching.

Pump curve – a graphic illustration of the relationship between flow rate and head for a particular mechanical pump.

PV – Photo Voltaics, or the process by which light is converted to electricity

PVC – poly vinyl chloride, a cheaper type of water piping sold in 6m lengths which are connected with integral compression gaskets or through special glue after surface preparation. The production and incineration of PVC produces dioxin, and its use in ecolodge projects is not recommended.

PWM – Pulse Width Modulated charge controllers turn on and off rapidly to keep batteries at full charge.

Recoil start – generator with a starter rope, found on smaller or lower quality generators.

Recovery rate - also called yield, the rate at which groundwater refills the casing after the level is drawn down. This is the term used to specify the production rate of the well.

Reinforced concrete – concrete cast with integral steel reinforcing bars, which give the composite material significant tensile as well as compressive strength

Remote Start/Stop – allows generator set to be started and stopped from a remote position with a manual button or an automatic switching system.

Risk – the probability that a particular level of loss will be sustained by a given series of elements as a result of a given level of hazard.

Risk analysis – a determination of the nature and extent of risk by analyzing potential hazards and evaluating existing conditions of vulnerability that could pose a potential threat or harm.

Risk assessment – a methodology to determine the nature and extent of risk by analyzing potential hazards and evaluating existing conditions of vulnerability.

Risk management – the systematic approach and practice of managing uncertainty and potential losses through a process of risk assessment and analysis and the development and implementation of strategies and specific actions to control, reduce, and transfer risks.

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RO – Reverse Osmosis, a process using semi-permeable membranes and high pressure to separate salts from water inside a series of tubes; typically used for desalination.

Rotor diameter – linear increase in diameter produces a squared increase in swept area: a Whisper 200 has 2.74m diameter rotor, and 5.90m2 area, whereas the Whisper 500 has a 4.57m rotor and 16.35m2

RPM – Revolutions per Minute – lower rotation speed in a wind turbine typically means higher durability and lower noise.

swept area.

Safety rope - plastic rope used to secure a borehole pump in case of pipe breakage. 7mm is the recommended minimum.

Septage – an odoriferous slurry (solids content of 3 to 10 percent) of organic and inorganic material that typically contains high levels of grit, hair, nutrients, pathogenic microorganisms, oil, and grease.

Septic tank – a tank that receives and partially treats sewage through the processes of sedimentation, flotation, and bacterial hydrolysis and gasification of the contents to separate solids from the liquid component, and which discharges the liquid component to a soil absorption system.

Single phase - 1Ф - typically 230V AC in Africa, is carried between two wires, live and neutral, and sometimes a third ground wire for safety, at 50 Hz. This is the power supplied from a normal wall outlet.

single phase = amperes x voltage (x power factor) / 1000

Site plan – a drawing of the construction site typically showing earth contours, buildings, water and electrical systems, roads and paths, and other important information.

Soak pit – a deep pit in the earth from which the liquid from a septic tank can be dispersed.

Solar array – a set of solar panels connected in series or parallel to collectively supply electricity to the electrical system. Typically arranged in 12v, 24v, or 48v, depending on system size and distance from the solar array to the battery array

Solar panel – also called a solar module, a configuration of PV cells mounted onto a hard base. Typically sold in units from 20w to 180w, these are mounted in arrays for most applications.

Sound attenuated – a shrouded generator which operates much more quietly than a normal generator. Typical values are 58 to 80 decibels.

Stabilization – the addition of admixtures such as lime, cement, polymers, or asphaltic solutions to a soil before compaction to improve water resistance and compression strength when saturated.

Static water level – depth of water surface in borehole under static conditions (not being pumped). May be subject to seasonal changes or lowering due to depletion.

Submergence - applied to submersible pumps, this is the pump’s distance beneath the static water level.

Submersible cable – electrical cable designed for in-well submersion, specified in millimeters, and connected to the pump by a cable splice.

Submersible pump – A motor/pump combination designed to be placed entirely below the water surface. Examples include borehole pumps.

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Sustainable Development – Development which fulfils the resource needs of the current generation, without compromising the needs of future generations. It is an imprecise term, but can be taken as meaning development that promotes economic, social and environmental benefits in the long term.

Swept area – area in m2

Three phase – 3Ф – is a more efficient use of conductors, whereby voltage is carried through three conductors, each 120° out of phase with the other two. Three-phase power provides a more efficient means of supplying large electrical loads like motors, or for transmitting power longer distances.

of a wind turbine rotor diameter in rotation. Coupled with average wind speed this determines the power output of the turbine.

three phase = amperes x voltage (x power factor) x 1.732 / 1000

Total dynamic head = vertical lift + friction loss in piping.

UV – ultraviolet light disinfection

Vernacular architecture – The dwellings and other buildings that reflect people’s environmental contexts and available resources, customarily owner- or community-built, utilizing traditional technologies.

Vertical lift – also called static head, this is the vertical distance that water is pumped, as calculated by the discharge level minus the intake level (even if this level is above the pump, as with a submersible pump). Horizontal distance does not add to the vertical lift, except in terms of pipe friction loss.

Voltage drop – the loss of voltage and power due to electrical resistance in a circuit; this can be minimized by the use of larger diameter cables or higher voltage current.

VSAT – Very Small Aperture Terminal is a small fixed earth station which forms a satellite based communication network for voice, data, or video conferencing.

Water tank – a storage container from plastic, steel, or concrete, which is typically designed in increments of cubic meters (1m3

Watershed – an area of land from which all of the water under or on it drains to the same place, which may be a river, lake, reservoir, estuary, wetland, sea or ocean.

= 1000 liters). Often, (2) 5000 liter tanks are cheaper than a 10.000 liter tank, due to transport cost of the very large tank.

WDU - Waste Disposal Unit, used in managing medical waste, which includes an incinerator, wastes and burned waste storage, shelter, security, starting fuel, tools, protective clothing, and recordkeeping. The De Montfort incinerator used in this system is a suitable model for incinerators used in lodge facilities.

Well seal – top plate of well casing that provides a sanitary seal and support for the drop pipe and pump.

Wellhead – top of the borehole at ground level. Typically the well casing is covered with a baseplate with threaded connections for plastic pipe from pump and too distribution lines.

Xeriscaping – landscaping with drought-tolerant plants.

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APPENDICES

Planning

Architectural Aspects

• Master Plan o Clientele – level of luxury, services o Clustered/dispersed units o Number of units o Type of central area, amenities o Staff Housing o Camping o Parking o Other features – landing strip, pool, footbridge, animal lookout, dock, etc. o Storm water runoff o Hiking trails

• Mechanical/Electrical Plan o Estimated demand, supply o Locate nodes – sources, consumption – aggregate when possible to reduce length of runs o Friction/resistance according to size, length, pressure/voltage o Size sources

• Aesthetics o Indigenous architecture? o Finishes, costs o Unit layout o Passive heating/cooling/ventilation considerations

• Construction type o Materials – local, imported o Unit type – tented camp, wooden cottages, etc. o Skills available locally o Materials available locally o Unusual features – tree house, elevated deck, multi-level, etc.

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Mechanical Systems

• Water o Source

Borehole River Roof Combination

o Purification Sand filtration Package unit UV Chemical

o Water Pressure Elevated tanks Pumping mechanisms

o Hot Water Solar Wood fired Propane Electric

o Grey Water Reuse for landscaping Leach fields

o Black Water – see Wastes, Waste Water • Wastes

o Human Wastes Waste Water

• Septic tank • Anaerobic digestion • Constructed wetland • Leach field • Ecological Sanitation – separation of urine and solids • Composting Toilet

o Solid wastes Collection Incineration Burial Removal offsite

• Plumbing o Low flow units vs. traditional

Toilets Showers Faucets

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o Sinks o Bathtubs o Main kitchen o Other – pool, landscaping, fire

• Electrical Supply o 12/24V or 120/240V o Generators o Photo Voltaic o Wind/water/etc.

• Lighting o Electric o Lamps

• Heat o Fire Places o Stoves o Solar

• Other systems o Communications

Radios Internet

o Refrigeration Electric Propane

Construction

• Storm Water Pollution Prevention Plan • Construction Logistics

o Truck Access o Material Storage o Construction Office o Tool Storage o Construction Erosion Control o Construction Staff Housing and Food

• Foundations o Rock Masonry o Reinforced Concrete o Earth Block o Concrete/Timber Pile

• Walls o Brick/Stone Masonry o Compressed Earth Block o Wood o Wattle and Daub

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o Fabric o Other

• Roof o Thatch o Iron Sheets o Asphaltic Sheets/Shingles o Tiles o Fabric o Cement – ferrocement, fabric/cement, etc. o Other

• Doors and Windows o Wood o Steel o Glass o Screen

Project Management

• Organization • Schedule • Budget • Logistics • Importation • Local Labor • Permits

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Site Selection Matrix

In many cases, the site for an ecolodge will be predetermined in the concession or will be a personal choice made by an individual owner or manager. A rational process can also be undertaken, whereby a matrix is constructed to evaluate two or more possible sites, which are then ranked in relation to the others, and then summed for final comparison, or a rating system such as 0 to 5 can be used. The Botswana Tourism Board created this example table for conducting such an evaluation139

:

139 Botswana Tourism Board, 41.

Site 1 Site 2 Site 3 SUITABILITY 1. Adjacent community 2. Proximity to road network (access) 3. Access to support services (staff, etc.) 4. Attractive views 5. On-site natural resources 6. On-site cultural resources 7. Multi-community potential 8. Access to wildlife viewing 9. Multi-activity potential 10. Compatibility: adjacent land 11. Remoteness + seclusion 12. Distance from airport 13. Four season potential 14. Waste water treatment CAPABILITY 1. Size of site 2. Available potable water 3. Expansion potential 4. Ownership 5. Overall response to market 7. Stakeholder concerns 8. Financial sustainability ENVIRONMENTAL IMPACT 1. Irreversible loss 2. Rare species 3. Landscape alteration 5. Disturbance of fauna

TOTAL

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Materials energy costs

Embodied Energy140

Material mJ/kg Notes Aggregate 0.1 Sand 0.1 Soil – rammed 0.45 Air dried hardwood 0.5 Concrete Block – 8MPa 0.6 Concrete Block – 10MPa 0.67 Concrete 1:4:8 0.69 Soil:cement .7-.85 Concrete Block – 12MPa 0.71 Concrete 1:3:6 0.77 Concrete 1:2:4 0.95 Mortar 1:6 0.99 Stone 1 Mortar 1:1:6 1.18 Mortar 1:4 1.21 Concrete 1:1:2 1.39 Kiln dried hardwood 2 Fired brick 2.5-3 Asphalt 2.6 Timber 3.4-8.5 Autoclaved Aerated Concrete Block 3.5-3.6 Plaster board 4.4 Portland cement 4.6-5 Lime 5.3 Refractory brick 5.5 Granite – locally dimensioned 5.9 Glass 12.7-15 Granite – imported 13.9 Plywood 15-24.2 Steel reinforcing bars 24.6 Steel – structural framing 25.4 Steel pipe 34.44 Steel – Galvanized sheets 39 Bitumen 46 Plastic – PVC pipe 67.5-80 Paint 68 Plastic – HDPE pipe 84.4 Plastic – ABS 95.3 Epoxy Resin 139.3 Cotton Fabric 143 Aluminum 155-170

Material mJ/m 2 PV Panel – thin film 1305 PV Panel - monocrystalline 4750 PV Panel - polycrystalline 4070

140 Milne, Geoff and Chris Reardon.

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Project schedule

This is an example Gannt Chart style project generated in MS Project for a hypothetical lodge construction.

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Tool list

The following list describes the tools necessary to build a remote lodge of four compressed earth block cottages, a main lodge building of earth block and thatch, various maintenance buildings, and rammed earth staff accommodation with iron sheet roofs. The workforce for this project will average 25 workers.

Corded Powered Tools (will require generator) Concrete mixer - ~1-200 liter (rent) 1 Stick Welder 1 Grinder (ie Bosch GWS20) 1 Electric Hammer Drill – 1/2" ~8amp 1 Router with masonry bit 1 Sliding Compound MitreSaw (DW718) 1 Table Saw (Dewalt DW744XPS) or similar 1

Cordless Tools 1/2" 36v Cordless Hammer Drill (ie Panasonic EY6450GQKW) 1 36v Circular Saw (ie Panasonic) 1 36v Reciprocating Saw (ie Panasonic) 1 Chain Saw (Stihl MS 280-1) 1

Skilled Tools Generator (to satisfy Lodge requirements later - 6KW Min) 1 Builder’s Level 1 Abney Level 1 100m tape 2 30m tape 2 Hand tapes 6 Mason’s String 500m Builder’s Square 3 Wire Brush 2 Trowels (large & small, each) 6, 4 Spirit Levels (2m, 1m, 40cm) 2, 3, 4

Semi-Skilled Tools Masonry hammers 4 Wood hammers 4 2kg hammer 2 Chisels 4 Files (rough, medium, fine, round) 2,1,1,2

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Hand operated drill 1 Wood saw 10 Metal saw 4 Bow Saw + Spare blades 2 Socket Set 1

Unskilled Tools Shovels 12 Pick Axe 2 Spade 6 Wheelbarrows 8 Buckets (12 liter) 20 Heavy Duty Water Hose 100m Treadle Pump 1 10.000 liter Water Tank 2

Other items: Extension Cables (100v and 230v) 5x25m, 5x25m 25l Jerry Cans 4 Driver bits Drill Bits Extra Saw Blades, (chain saw, mitre saw, reciprocator...) Consumables (Welding rods, chain oil, etc)

Generator Efficiency

This table lists average fuel consumption of large generators by capacity141.

Generator Size (kW)

Generator Size (kVa)

1/4 Load (l/hr)

1/2 Load (l/hr)

3/4 Load (l/hr)

Full Load (l/hr)

20 25 2.3 3.4 4.9 6.1 30 38 4.9 6.8 9.1 11.0 40 50 6.1 8.7 12.1 15.1 60 75 6.8 11.0 14.4 18.2 75 94 9.1 12.9 17.4 23.1 100 125 9.8 15.5 22.0 28.0 125 156 11.7 18.9 26.9 34.4 135 169 12.5 20.4 28.8 37.1 150 188 13.6 22.3 31.8 41.3

141 http://www.dieselserviceandsupply.com/Diesel_Fuel_Consumption.aspx

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Concrete Mixes by Volume and Use

This table can be used to choose cement ratios and to estimate required quantities142

.

142 Indian practical Civil Engineers' Handbook, Section 20, found in Helvetas Nepal Bridge Building at the Local Level Short Span Trail Bridge Handbook.

Type of Cement Work

Mix. proportions Cement : Sand : Gravel

Dry required quantities for one cubic meter wet: Cement

bags @ 50 kg

kg Sand [m3

Gravel[m] 3

Stones or Boulders

[m] 3]

Cement Mortars

1 : 1 - 1 : 2 - 1 : 3 - 1 : 4 - 1 : 6 -

20.4 13.6 10.2 7.6 5.0

1020 680 510 380 250

0.71 0.95 1.05 1.05 1.05

- - - - -

- - - - -

Cement Plaster (20mm w/12%

waste)

1 : 4 - 1 : 6 -

0.18 0.12

9 6

0.024 0.024

- -

- -

Cement Stone Masonries

1 : 4 uncoursed stone 1 : 6 masonry

2.66

1.75

133

87.5

0.37

0.37

- -

1.2

1.2

1 : 4 coursed stone 1 : 6 masonry

2.28

1.50

114

75

0.32

0.32

- -

1.25

1.25

Cement Concretes

(plain or reinforced)

1 : 4 : 8 1 : 3 : 6 (M10) 1 : 2 : 4 (M15) 1 : 1½ : 3 (M20)

3.4

4.4

6.4

8

170

220

320

400

0.47

0.46

0.45

0.42

0.94

0.92

0.90

0.84

- - - -

"Plum" Concrete

1 : 3 : 6 with 50% boulders 2.64 132 0.28 0.54 0.50

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CEB Block Cost Comparison

Hydraform Makiga

230mm x 220mm x 115mm (l x w x h) = .02645 m2/block + 0mm mortar ≈ 38 blocks/m= .0058190 m

2

3/block ≈ 172 blocks/m

3

70 blocks/50kg cement – 5% blocks 40 blocks/50kg cement – 8% blocks

150 blocks/person/day

295mm x 150mm x 105mm (l x w x h) = .04425 m2/block + 15mm mortar ≈ 20 blocks/m= .0046463 m

2 3/block ≈ 215 blocks / m

3

120 blocks/50kg cement – normal blocks 80 blocks/50kg cement – strong blocks

100 blocks/person/day Advantages: • 1500-2000 blocks per day • Wider block = more stable wall – good for two

story construction • Possibly better quality control

Advantages: • Less expensive production • Low cost and remote applications • Machine cost is $400-$1200 • Longer block • Use by unskilled workers

Disadvantages: • Higher skill level required • Machine is $25,000 • Shorter block – requires more • Fuel required – 10-12 litres/2000 blocks

Disadvantages: • 400-500 blocks per day • Less uniform block typically • Narrower block = less stable wall – not

suitable for 2-story construction

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Erosion Control Measures

Minimize the Amount of Soil Exposed During Construction Activity • Preserve areas of native topsoil on the site wherever feasible. • Trenching activities will be conducted as narrowly as reasonable without jeopardizing worker

safety. • Sequence or phase construction activities to minimize the extent, duration of exposed soils. Phased Construction • Trenching operations to be conducted sequentially throughout the site. • Exposed pipe laying trench not to exceed one length (100m). Shorter lengths of exposed

trench are preferred. • Backfilling of trench to be accomplished quickly, with prompt compaction of wearing surfaces

and return of top soil and vegetation. • Seeding will be conducted where necessary. Maintain Natural Buffer Areas • Maintain natural buffer areas (8m) at stream crossings and around the edge of any waters. • Use perimeter controls adjacent to buffers and direct storm water into buffer areas • Mark boundaries of vegetative buffer with a combination of markings depending on the terrain

as with site delineation. • Ensure that water flowing through the area is not forming ponds, rills, or gullies due to erosion

with the buffer strip. Delineate Site • A survey crew will survey the project site and establish project boundaries and limits of

disturbance. • Surveyors will mark site with a combination of markings depending on the terrain, including

lath, flagging and/or construction stakes. • Areas that will be cleared, graded, or left undisturbed will be marked with flagging. • Crew to be instructed in site limits. Any activity to be conducted off site or in area to be left

undisturbed must be referred to site superintendent. Control Storm Water Discharges and Flow Rates • Divert storm water around the project site (silt fencing, straw wattle barriers, interceptor dikes

and swales, grass-lined channels). • Slow down or contain storm water that may collect and concentrate within the project site

(seeding, silt fence, straw wattles, sediment traps, settling ponds) • Avoid placement of structural control measures in active floodplains • Place velocity dissipation devices along the length of conveyance channels or where

discharges join a water course (check dams, sediment traps, riprap) Silt Fencing • Do not install silt fence in area of concentrated flows. • Only place silt fence at toe of slope. • Install silt fences along the perimeters of the site as the works proceed, and around the

topsoil stockpile. • Fence must be installed at right angle to slope. • Excavate 30cm deep trench along the line of proposed installation.

119

• Space wooden posts supporting the silt fence 1-2m apart and drive securely into the ground minimum 45-50cm deep.

• Fasten silt fence securely to the wooden post. • Backfill and compact after the verifying bottom edge of the silt fence is 6” deep minimum. Straw Wattle Barriers • Place straw wattle at the toe and on the face of slope. • Similar to silt fence, straw wattles should be placed on the contour. • Must be trenched (5-10cm deep) and staked. • On slopes, straw wattles should be placed at intervals depending on the degree of slope.

Protect Steep Slopes • Surface roughen (‘slope tracking’ or ‘cat tracking’) to provide small pockets for trapping runoff

and allowing infiltration. • Reduce steepness to less than 1 rise : 3 run (± 18°). • Rolled erosion control products will be placed on top surface if necessary. • Straw wattles along slope at intervals according to degree of the slope, and at toe of slope. • Silt fence at toe of slope. Surface Roughening • Run tracked machinery along the fall line of the slope with the blade raised. • Avoid compacting the soil surface. • Cover the slope with no more than one foot between tracks. • Roughened areas should be seeded and mulched immediately. Interception/Diversion Ditch • Perimeter control usually consisting of a dike or a dike + channel • Construct along the perimeter and within the disturbed part of a site. • Construct a ridge of compacted soil (often accompanied by a ditch or swale with a vegetated

lining), at the top or base of a sloping, disturbed area. Dust Control • Dust control will be implemented as needed once site grading has begun and during windy

conditions (30kph or greater) while site grading is occurring. • Spraying of potable water by hose from the existing water distribution system or by mobile

truck.

Retain Topsoil • Top soil stripped from the immediate construction area will be stockpiled. • The stockpile soil will be located at least 8m away from concentrated flows. • The slopes of the stockpile will not exceed 2:1 to prevent erosion. • A silt fence will be installed around the perimeter of the stockpile. • Also consult ‘Protect Steep Slopes’ erosion control measure.

120

Biogas Digester

The following versatile design comes from the Dutch organization SNV in Kigali, Rwanda:

Dimensions of Different Components

Components Symbol Dimension per size in cm 4 m 6 m3 8 m3 10 m3 3

Length of Outlet L 140 o 160 170 190 Breadth of Outlet B 120 o 130 140 160 Height of outlet H 50 o 55 60 62 Radius of digester R 110 d 130 145 155 Radius of pit R 140 p 160 175 200 Height of digester wall H 80 c 85 90 95 Depth of pit (excavation) D 160 p 170 180 190 Height of Dome H 65 dom 70 75 80 Radius of curvature of dome R 126 dom 156 178 190 Inner height of digester and dome H 145 all 155 165 175 Height of max. slurry displacement H 25 d 25 25 28 Height of outlet passage H 105 op 110 115 123 Concrete dome thickness 20-7 20-7 20-7 20-7 Size of manhole 60 x 60 60 x 60 60 x 60 60 x 60

121

Grease Trap

Septic Tank

122

Water Tank

123

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