Resource Recovery, Reuse, and Environmental Remediation in the Ecotourism Industry of Costa Rica

For:  [-redacted-]

Manuel Antonio Costa Rica

By:  Osa Water Works, S.A.

Puerto Jiménez Costa Rica

February 18, 2007

1.0  Executive Summary

Use of the existing [-redacted-] laundry waste stream as irrigation water would cost five times less than application of the same amount of municipal water presuming modest additional water treatment is needed and 30 times less if not additional treatment is required.  The volume of daily wastewater would provide adequate irrigation for two hectares of grounds.  When economically compared to irrigation with municipal water, greywater reuse is economically favored hands down.  However, when compared economically to the alternative of not irrigating at all, then the decision hinges around aesthetic values rather than purely economic ones, making economic analysis imprecise at best.  Reuse of laundry wastewater as irrigation water is an environmentally responsible way of husbanding resources, therefore, if the alternative is to irrigate with city water.  It is no panacea to overall wastewater management, however.  If greywater is dispersed during the rainy season as a means of disposing of used water, the adverse environmental consequences are likely to exceed those of overcharging already strained leach fields in subsoil disposal.  The armchair evaluation elucidated in this report demonstrates that laundry water reuse is an environmentally sustaining activity likely to be worthwhile and viable for five months of the year and of no environmental benefit whatsoever for the remainder of the year with a return on investment measured more in environmental kudos than in dollars and cents.   

2.0   Introduction and Objectives

Osa Water Works, S.A. (OWW) was contracted primarily to determine the viability of reusing laundry wastewater at [-redacted-] as irrigation water for facility ornamental gardens and green zones.  This report primarily summarizes the economics and practical viability of laundry wastewater reuse for irrigation purposes in the context of existing infrastructure, conditions, and operations.  Beyond this primary objective, however, three secondary lines of inquiry were addressed.  The full list of report objectives are bulleted below.

• Feasibility assessment of using laundry wastewater as irrigation water

• Provide recommendations for management of the water quality of the recycled stream water used in the crocodile habitat.

• Viability of constructed wetlands to remediate reserve stream water

• Commentary on the migration from an exclusively municipal water supply to one augmented by ground water.

3.0    Environmental Sustainability through Resource Optimization

Commercial resource optimization increasingly involves methods that were developed and deployed in the industrial and manufacturing sectors of developed nations mostly in the last three decades to either reduce the amount of resources required to achieve a commercial operation or to reduce the waste by-products of that operation.  Whereas basic costs of manufacturing or commercial endeavors have always rationally included the costs of capital investment, ingredients, and human services necessary to create the commercially viable product being marketed, the costs of waste management were discounted or disregarded throughout nearly all of modern history.  It was not until the sixties that the decay of environmental quality in industrial societies shifted the focus of industrial managers to include such concepts as waste minimization, resource recovery and re-use, and efficiency optimization.  Since then, these operational principles have become de rigeur standards of commercial operations throughout the industrialized world and necessarily of significance to an environmentally sensitive commercial operation such as the top-end eco-tourism sector that represents the [-redacted-]’s commercial market.

While the hotel is an eco-lodge in a pristine natural environment and not a company manufacturing widgets in America’s rust belt, its laundry wastewater is analogous to an industrial by-product, and industrial premises that have gained coinage in the past four decades are useful within which to frame choices available to [-redacted-] management.  For instance, consider the following proactive buzzwords:  product substitution, waste minimization, and resource recovery in the context of laundry waste at the hotel.

3.1  Product substitution

Since detergents constitute one of the primary contaminants in a laundry waste stream, the ability to replace detergents with a technology that creates fewer contaminants obviously represents one avenue toward the ability to reduce the environmental impact of laundry operations.  Ozone/silver based laundering systems have recently been developed that strive toward this goal.  However, they are technologically still somewhat prototypes and are not sufficiently versatile or effective for dependable commercial operation in an aesthetically sentistive application such as the [-redacted-] laundry operation. 

3.2   Waste minimization

For laundry, the only way to reduce the waste stream is to reduce the loads of laundry required or to purchase equipment that launders effectively with reduced volumes of water and/or detergents.  Based on cursory market reviews, it is apparent that wholesale replacement of equipment with conservation equipment will achieve only modest reduction in wastewater production and at non-trivial capital costs.  Also, like ozone laundering systems, conservation systems are unlikely to be appropriate for commercial operations with aesthetic sensitivities.  [-redacted-] already practices waste minimization in one important operational policy.  By offering clients the opportunity to decline the implicit obligation of applying freshly laundered sheets to beds, the hotel actively encourages the guest to engage in environmental awarness and proactive conservation. 

3.3   Resource Recovery.

The reuse of waste products from the laundry operation represents the most viable means of achieving meaningful optimization of resources for the laundry operation.  There are two useful resources present in the wastewater: heat and water.  Proprietary re-use systems are on the market that target commercial and industrial laundry facilities.  However, it is probable that the laundry operation at [-redacted-] is not large enough for the capital and operating costs of such a system to be viable.

4.0              Water Quality:  Terms and Definitions

The objectives of the investigation all hinge to some degree upon the contaminant matrices of varying natural and artifical water streams, including wastewater (laundry waste), process water (crocodile habitat), and natural water (contaminated reserve stream).  A brief discussion of water quality contaminants of relevance to the ensuing discussion is provided below.

4.1             Total Suspended Solids (TSS)

Total suspended solids (TSS) consist of the insoluble particulate matter that is introduced to the wastewater by the dirt that is laundered from clothing.  This material is more dense than water and is best removed though sedimentation or particulate filtration.  It is likely that the vast majority of TSS is removed from the raw wastewater during passage through the existing slow-sand filtration system in use.

4.2              Fats, Oils, and Greases (FOG)

Fats, oils, and greases (FOG) are also introduced to the waste stream by the dirt contained in the clothing being laundered.  FOG are not soluble in water—or only mildly soluble—and exist as suspended solids, colloidal suspensions, and in some cases as emulsions within waste streams.  Unlike total suspended solids, FOG is less dense than water and tends to rise under quiescent conditions (such as above the filter beds where the sheen of oils can be seen on the surface of the standing wastewater).  Some of this material is physically separated by the slow-sand filter and some portion of this contaminant—perhaps greater than half—is likely to be removed through both filtration and biologic oxidation within the filter itself.  FOG introduces odor and may have visual nuisance qualities as well, but the most adverse impact of FOG in a water reuse system is expected to be as a fouling agent of nozzles, valves, drip holes and to be a challenge to the efficiency of transmission and distribution.

4.3              Soaps and Detergents

Surfactants are molecules that have one polar end and one non-polar end.  The non-polar end attaches itself to organic materials (FOG and other organic compounds), and the polar end attaches itself to the water molecule.  This quality of having both organophyllic and hydrophyllic ends makes detergent molecules work to cut grease in water.  Because there are anionic, cationic, and non-ionic surfactants, treatment systems predicated on ion exchange are sadly not universally applicable to all detergent waste streams.  Ultra- and nano-filtration are operationally cumbersome, and reverse osmosis is a capitally and operationally intensive unit operation for this application.  Soaps and detergents are conservative molecules not highly susceptible to bacterial degradation and are unlikely to be oxidized or adsorbed in significant amounts at any stage of the existing greywater treatment train at [-redacted-].  Soaps and detergents are mildly toxic to bacterial assemblages and are detrimental to the efficacy of septic or activated-sludge microbial assemblages.

4.4              BOD-5

Five-day biochemical oxygen demand (BOD-5) is an analytical measure of the biodegradable portion of organic contaminants in a waste stream.  Typically, BOD-5 comprises dissolved organic contaminants, which are the most accessible to bacteria and therefore cause the most severe and immediate stress on natural waters.  The consumption of BOD-5 by bacteria results in the rapid consumption of dissolved oxygen, the metabolic electron acceptor of choice, which in turn adversely impacts the microbial and macrofaunal populations of receiving streams.  It is expected that a portion of the BOD-5 in the laundry waste—perhaps 20%--is removed by facultative bacteria in the slow sand filter at use at [-redacted-].

4.5              COD

Chemical oxygen demand includes all organic contaminants, not just the biodegradable ones, and is a measure of the ultimate oxygen demand of all organic contaminants and reduced inorganic species.  It necessarily includes all FOG, all organic surfactants, and any other organic contaminant that is introduced to the waste stream.  It is not as precise an indicator of environmental quality as BOD-5 because it includes contaminants that are not biodegradable as well as reduced inorganic species in some cases which do not immediately suppress oxygen concentrations and thereby threaten healthy aquatic assemblages.  But COD is the best of all analytes for system design and process control because it is an easy analytical test to perform, taking less than an hour while BOD-5 takes five days.

5.0  Water Quality Requirements of Irrigation Water

In order to re-use laundry waste as irrigation water, the wastewater must meet basic standards of quality in two important regards.

5.1  Botanical limitations.

Some of the components of laundry waste most resistent to septic-tank or municipal wastewater treatment are phosphate- and nitrate-rich surfactants that coincidentally make good plant fertilizers.   While a bit of this material is likely to promote plant growth, different plants react to different compounds and circumstances in different manners.  Some plant species are sensitive to high sodium concentrations and would not be expected to perform well under grey water irrigation, since most detergents are rich in sodium.  Similarly, plants that prefer acidic soils may not favor the typically alkaline pH of most greywater waste streams.  Also, there is a natural threshold for bio-uptake of nutrients as well.  In sum it is not possible to predict how an assemblage of ornamental or natural plants will react to the contaminant matrix of the [-redacted-] laundry wastewater following the slow-sand filtration this waste receives.  To determine the botanical limitations of existing wastewater quality will require sample test plots in which varying amounts of water are applied to determine the range in botanical tolerance and to identify any aesthetically objectionable consequences.

5.2   Mechanical limitations

In order to distribute irrigation water efficiently, it is best that suspended sediments, and FOG be in concentrations as low as possible to inhibit accumulation or interference in drip holes, irrigation nozzles, valves, and other parts of the irrigation distribution system.   While there may be some latitude of mechanical tolerance for some contaminants, it is relatively easy to reduce sediment loads to beneath detection levels, and this should be the same objective for FOG if practical.  The first thing in determining the practicality of reducing FOG is to determine what the existing FOG levels are at all stages of the waste train and to experimentally determine both the mechanical tolerance to these contaminants as well as the cost of removing FOG to reduce mechanical interference.

6.0             Existing Grey Water Treatment Train

As the photos below reveal, [-redacted-] employs a somewhat extensive treatment system for the pretreatment of laundry waste prior to its diversion to leach fields for final disposal.  The systems in place include:  1)  preliminary settling;  2)  geomembrane filtration;  and 3) slow-sand filtration.  All of these operations provide for the mechanical separation of suspended solids from the wastewater.

The slow-sand filtration operation, however, is also a biological unit process that achieves oxidation of organic material and not just mechanical filtration of solids.  The slow-sand filter operates under saturated conditions and depends on facultative and anaerobic microorganisms in the intergranular porosity to degrade dissolved organic material contributing to BOD-5.  Much like the aerobic activated sludge system for treatment of septic wastes, these bacteria consume organic compounds and emit gaseous waste products.  However, slow sand filtration depends upon nitrate and nitrite as electron acceptors instead of oxygen in activated sludge and excretes laughing gas (nitrous oxide) and other nitrogen compounds rather than the carbon dioxide produced from aerobic metabolism.  Facultative and anaerobic metabolic pathways are much more energetically cumbersome than aerobic metabolic pathways and as a result biodegradation takes much longer to achieve the same degree of treatment.  The end result is that slow-sand filtration is likely to remove some, but by no means all, of even the dissolved organic contaminants present

The product wastewater from the laundry treatment system has every appearance of being amenable with only modest additional treatment to be adaptable for irrigation purposes.  Whether this is true or not cannot be theoretically established.  It can only be done through experimentation at the facility and through analytical quantitation. 

If testing reveals that additional treatment is needed, then the unit operations alternatives could involve nanofiltration, micro-filtration, reverse osmosis, ion exchange, or advanced oxidation to target the surfactants in the water, OR either biologic or advanced oxidation to target organic compounds in the water.  Since only one technology efficiently addresses the reduction of both contaminant types, it is likely that advanced oxidation may represent the most favorable unit operation if additional water treatment is necessary in order to successfully apply product laundry water as irrigation water.  Until testing has revealed additional treatment is necessary, experimental testing of advanced oxidation treatment alternatives would appear premature.

7.0 Feasibility Analysis of Greywater Reuse

7.1  Wastewater generation

[-redacted-] uses four washing machines with rating capcities of 30, 35, 50, and 80 pounds.  Each machine has five fill cycles and is estimated to complete its wash cycle in 30 minutes.  The machines operate continuously from seven a.m. until ten p.m.  If we assume that the net capacity of all the machines jointly is 150 gallons, the total amount of wastewater generated during a 24 hour time period is given by the following calculation:

150 gallons * 5 cycles per wash * 2 washes per hour * 17 hours per day = 25,500 gallons per day.

A daily wastewater production rate of 25,500 gallons translates to 17.7 gallons per minute.  This means that any supplementary treatment system (should it be shown by experimentation to be required) must have a capacity for at least this process flow rate.  It also means that the end destination—i.e. use as irrigation water—should have a water demand comparable to the production supply if the water re-use model is to have functional viability.

Lawn irrigation in the tropical environment requires on average the daily application of 5 mm of water daily.  For one hectare, the equivalent of 5 mm of rain is 50 cubic meters, or 13,228 gallons of water.  Correspondingly, the amount of laundry wastewater produced in a single day (just under 26,000 gallons) is adequate to provide irrigation coverage for nearly 2 hectares of grounds if the botanical water requirements are like those of lawn grasses.  Grounds maintenance or landscaping consultants may decide where the irrigation water is most useful in which amounts to determine how to optimally distribute the water that is available to the range of plants comprising green zones.

Having satisfactorily established an approximate correspondence between irrigation water demand and wastewater supply, the next step in the feasibility evaluation process is to compare the economics of the operational alternatives to determine how the projected costs compare with those of alternative means of irrigation or the costs of non-action.

For an economic analysis we must compare two specific courses of action to one another and compare the costs of each.  For this study, two alternatives were compared economically.  For the first—an apples to apples comparison—an economic analysis was prepared to compare the costs of irrigation with city water versus with the costs of using treated wastewater.  In the second case an apples to oranges comparison was made between the alternatives of a wastewater irigation system and no action at all.

7.2             Case One:  Economic Anaylsis:  A y A vs Treated Laundry Waste Irrigation

We can assume for the Case-One comparison that for both systems some components will be common and can be excluded from comparison.  For instance, for either type of irrigation system, a distribution tank will be required as well as the irrigation piping mains, feeder lines, drip nozzles, spray heads, etc.  Correspondingly the list below summarizes the components that are required for the wastewater reuse system that are not required for irrigation with city water.  Approximate capital costs are provided for each of these components.

1)     Treatment system:  $3000 (it is not known before testing if this will be required but has been included in this analysis to consider the most expensive case

2)     Two inch pipeline to deliver wastewater to holding tak:  $2000

3)     Storage tank to receiving treated wastewater before it is pumped to the distribution tank at the top of the grounds:  $500

4)     Pump:  $500

5)     Labor and profits:  $3000

6)     TOTAL CAPITAL:  $9000

If we assume replacement of the pump every five years, the treatment system every ten years, and the storage tank every twenty years, we determine that across twenty years, capital costs amount to around $15,000, or $750 capital costs per year assuming a linear amortization model for a monthly capital cost equivalence of $62.50.

Assuming supplemental water treatment is achieved with advanced oxidation and requires an application of 10 mg/L hydrogen peroxide, 25,000 gallons will require 0.945 kg of pure hydrogen peroxide, or 2.7 kg of 35% industrial grade per day.  The price of industrial strength hydrogen peroxide is around $8 per kg, so the treatment regimen would represent a monthly cost of around $648,

Pump sizing to provide delivery of 25,000 gallons of water daily across a head of 60 feet presupposes a pump of 4 horsepower, which will use about 4.3 kw assuming a 70% efficiency.  Since it delivers 100 gpm, it is expected that the pump will be operational 4.2 hours per day and provide a monthly electrical power demand of 543 kw-hours.  The ultraviolet for the advanced oxidation system draws 20 watts 24 hours per day for a total monthly power demand of 14.4 kw-hours.  The total monthly power demand, therefore, is expected to be around 557 kw-hours.  Since the commercial rate for each kw-hour in Manuel Antonio is 78 colones, this monthly power draw corresponds to an anticipated monthly power demand of the system of C43.446, or around $84.40.  If we add our amortized capital costs and possible chemical costs to this monthly operational cost, we have a total of $795.  Since municipal water costs $1.22 per cubic meter, the monthly fee for the application of 26,000 gallons daily of irrigation water amounts to $3600.  Clearly, in an apples to apples comparison, economics favor the recovery and reuse of laundry water over irrigation by a factor of nearly 5 times presuming modest water treatment requirements.  If the water can be used with no water treatment, then laundry re-use is around thirty times less expensive than using the equivalent amount of municipal water.

7.3              Case Two:  Economic Anaylsis:  Treated Laundry Waste Irrigation vs No Irrigation

In an apples to oranges comparison, we can economically compare the cost of using laundry waste for irrigation versus the cost of doing nothing.  In this case, the subjective cost of “no action” devolves to the aesthetic negative of plants becoming stressed from lack of water.  It is difficult to anticipate that the hotel would sacrifice business over this, and it is clumsy to attempt to assign an economic value to the perception of floral vibrancy among guests, staff, and the hotel ownership.  However, if the water does not require additional treatment, then the daily operational costs of $3 in electricity may seem very little in comparison to having verdant gardens.  If water treatment is required to use this water, then the costs may swell to the point of non-viability (around $26 per day).  Without additional testing it is not possible to anticipate if the water is adequate or not for distribution and irrigation duty without further treatment.

8.0              Crocodile Habitat Recycle Water

At present the crocodile habitat is sustained by pumping stream water from an adjacent watershed into an artificial zoological habitat for crocodiles.  The habitat water is recycled at present.  Periodically, every 2-3 weeks, this water is discarded and new water is introduced. 

While the water is recycled it is subjected to concentration by evaporation and from the introduction of waste matter generated by the reptiles themselves.  Furthermore, the non-natural environment is expected to experience non-natural permutation of water chemistry through unintended natural phenomena, particularly through the activity of microbial algae and bacteria in the recycled habitat water.  The color of the water is light brown, like tea, a result of tannins accumulating, presumably from the decay of organic material suspended in the water or in contact with the water.

Either biological treatment or advanced oxidation is expected to provide substantial water quality improvement to increase the number of times that water can be recycled.  Both operations have favorable and unfavorable characteristics, but overall advanced oxidation is the tidiest, neatest, most sophisticated, and least obtrustive, so for [-redacted-], it is thought that an advanced oxidation unit will be the optimal treatment operation to augment the number of water reuse cycles achievable while optimizing water quality and aesthetics through color elimination with each successive cycle.

9.0  A Modest Proposal

Greywater reuse, segregation, and management, is obviously not an issue unique to [-redacted-].   But it is an issue that is common to a huge swath of commercial enterprises across the world.  Laundry waste is one of the largest human waste streams in existence, and inroads into its optimal management may represent significant milestones in the approach to sustainable living within a modest environmental footprint.

[-redacted-] has its laundry waste segregated from blackwater and has an operation in place that already pretreats this water.  Therefore the hotel has an existing infrastructure that is nearly ideal for testing grey water reuse in the real world, not just for its own benefit but also of potential benefit to the development and popularization of increasing standards of environmental sustainability in general through reporting and documentation.

For both crocodile habitat water and for laundry wastewater re-use, there exists some criterion for action, whether rigorous and analytical, or simply subjective and arbitrary.  The first recommendation of this report is to establish base level criteria for action or decision that are not subjective.   For instance, both cases are detailed below.

9.1  Baseline Characterization:  Irrigation water.

There is value in knowing the range in water quality that is tolerated by plants.  There is also value in knowing the degree to which existing treatment regimen is effective in reducing contaminants in the waste stream.  The only way to know if the the water can be successfully used on a large scale is to try it out on a small scale and to quantify water quality during trials so that if fouling of nozzles or plant damage is observed there will be a rational basis for testing to determine acceptable water quality ranges for the duty desired.

1)     9.1.1  Analytical determination.  For both raw wastewater and final product wastewater, determination of the following analytical variables to assess the contaminant matrix and to determine pretreatment efficiency:

a.      Total Suspended Solids

b.      pH

c.       BOD-5

d.      FOG

e.      COD

f.        Total surfactant concentration.

2)     9.1.2  Sample irrigation plots.    To determine the biologic tolerance for wastewater irrigation, sample plots of one square meter should be erected.  In each plot different amounts of treated laundry wastewater should be applied to simulate irrigation of different amounts, including half the anticipated daily loading, the full daily loading and two times the daily loading (for example).  The biology department should select the plants to include in this study and to use standard measures of botanical health to gage the response of the flora to the variable irrigation application rates.  Aesthetically objectionable results should be factored alongside plant response information to determine overall viability.

9.2  Baseline Characterization:  Crocodile Habitat Water

For the crocodile habitat water, criteria should be established for a minimum degree of acceptable water quality.  Since the reptiles on display are capable of tolerating large ranges in water quality, it is likely that the criteria for water treatment or water replacement will not be predicated on animal health but rather on the perceptions of visitors to the display and any nuisance effects observed, particularly odors.  There is nothing overtly objectionable about the tannic color of the water, since crocs commonly frequent tannic swamp water anyway.  Once a criterion is in place for the level of water quality required for the aesthetic demands of the exhibit, then it will be possible with a portable HACH spectrophotometer kit to determine when the water should be replaced with new water.  Also, with the establishment of a baseline water quality requirement, it becomes possible to experimentally evaluate the economics of treatment alternatives, including advanced oxidation or biological treatment.  For the crocodile habitat water, the critical water quality parameters upon which to establish a criterion for replacement and treatment and the determination of a minimum standard of water quality are the following:  pH, BOD-5, and COD.

9.3  Baseline Characterization:  Polluted Stream Water

The stream water flowing through the [-redacted-] nature preserve is visibly contaminated with raw sewage and has a notable odor that would be hard for any visitor to fail to detect upon visiting the preserve.   While a constructed wetland might well be able to provide substantial remediation to the stream water quality, it is impractical to contemplate this or any alternative without some baseline information upon which to consider alternatives.  For the stream water, variables to consider measuring are the same as in the Crocodile habitat, pH, BOD-5, and COD.

9.4  Experimental Alternatives:  Irrigation and Crocodile Habitat Water.

If it is determined that the application of laundry wastewater requires additional water treatment, either for botanical health or to reduce maintenance and distribution interference, it is recommended that advanced oxidation be considered first to determine if the economics favor the deployment of this operationally simplistic treatment alternative.  Its primary advantages are that it is small and compact and uses chemicals that decay to oxygen and water so that no environmental degradation is possible through use of the treatment alternative.  The footprint of the unit operation is similarly small, consisting of a unit that takes up less than one half square meter in area and weighs less than 20 kg.  By determining baseline measures of water quality using chemical oxygen demand as one of the analytes, it is possible to experimentally adjust oxidant feed rate and the process flow rate and use COD as the process control variable, making experimentation fast and concise.  The experimental equipment needed to determine the viability of advanced oxidation for final laundry water polishing (IF NEEDED AT ALL) and treatment of crocodile habitat water consists of the following, with costs of each element approximated parenthetically:

1)     8 gpm ultraviolet disinfection chamber ($800)

2)     Dosimetric pump ($250)

3)     Hydrogen peroxide

4)     HACH spectrophotometer ($2500)

5)     COD reaction crucible ($500)

6)     Reagents for testing

7)     pH meter ($800)

In essence the same equipment is needed with little variation for the actual process equipment and control analytics for advanced oxidation, so the experimental equipment would represent de facto pilot testing equipment and would represent a capital investment not expected to exceed $5000.  If the tests were to prove favorable and the economics of hydrogen peroxide were within acceptable limits, then scaling to full operation would carry few additional capital costs.

9.5  Experimental Alternative:  Stream Water Remediation

Once the baseline stream water quality is established through testing over a period of time, simple scholarship will determine whether aquatic uptake is capable of remediating the stream water quality to standards established as baseline goals.  Since there is no practical way to bench test a constructed wetlands, it will be most practical upon deciding to test the viability to construct a pilot wetlands at the head of the property.  Some hydrographic contouring may be required to conform with optimal configuration of constructed wetlands.  Particularly, the stream has a fairly defined channel, and it may be necessary to groom a shallow marshy area on either side of the stream channel and divert water there to provide for optimal hydrology for the plants that will be used to uptake nutrients and provide for BOD removal.  On the basis of waste removal demonstrated as a function of area vs depth of the constructed wetland, it will be possible to determine the total area required to remediate the stream water quality to a target level determined by the [-redacted-] biology department in consultation with MINAE and permitting authorities and based on those findings can then calculate the area that will be required to provide for full remediation and whether it is in the hotel’s interests to under-write the appropriate-technology remediation strategy as a permanent commercial contribution to the Manuel Antonio semi-urban tropical environment.

10.0  Water Supply Migration from Municipal to Ground Water

[-redacted-] is presently drilling a water well.  After two weeks of drilling with a cable-tool rig, the drillers were at 59 meters in depth at the time of the site visit for this report, out of an anticipated 80 meters total depth.  At present only modest water has been hit, according to drillers.   

Based on the completed well yield and analytical determination of ground water quality, it will be possible to provide recommendations regarding pressurization, storage, pumps, water disinfection, and other issues directly relevant to boosting or surplanting the existing municipal water supply with onsite ground water.   Until well yield and water quality is assessed, no meaningful conclusion is possible.

11.0  Conclusions

The issues discussed in this report do not represent operational issues vital to the success of hotel business operations.  Nor are they issues that necessarily provide dramatic economic incentives to make changes.  However, the net effect of laundry water reuse, increased degree of reuse in the crocodile sanctuary, remediation of the reserve stream water are all issues that have modest to dramatic environmental and aesthetic benefits.  Whether those benefits can be parlayed into an economic advantage and whether they outweigh the capital and operational costs of instituting them is a decision that will be predicated largely on the not-completely-tangible value of environmental conservation and protection.  While the concept of environmental sustainability remains incompletely defined and still somewhat subjective, there is no doubt but that in the ecotourism business, perceptions are critically important.  But more striking, doing even a little bit at a non-trivial capital and operational cost may have a greater ultimate benefit than doing nothing at all at no cost whatsoever.  However, if the solutions can be devised to achieve a little bit or even more at modest capital and operational costs, or ideally at a net savings, then the overall reward from taking the proactive options become even more attractive.  However, to even begin to practically evaluate the real feasibility requires a baseline data collection program and a commitment to a scientific testing regimen to determine feasibility on the basis of measurable criteria, according to a process in which results can be duplicated and scaled.

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