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Manual de mantenimiento para reedbeds
Reedbed maintanence manual.
The purpose of this manual is to document the reedbeds in the local area, to improve maintenance, and to promote water treatment education.
El proposito de este manual es documentar los reedbeds en la zona, mejorar el mantenimiento, y promover la educacin de tratamiento de agua.
Books / Reports / Directories
Scanned by Monteverde Institute.
The State of Water in Monteverde, Costa Rica: A Resource Inventory.
R EED b ED M AINTANENCE M ANUAL Silvia Newell Daniel Craig Scott Harlow In cooperation with: The Monteverde Institute Monteverde, Puntarenas Costa Rica Apdo. 69-5655 2005
R b MM Â– 1 Table of Contents PART I Â– General Information Pps. 1-6 Table of Contents 1 Introduction 2 Statement of Purpose 3 Maps (Costa Rica, Monteverde) 4 Reedbed Basics/Â“Kit of PartsÂ” 5-6 PART II Â– Case Studies 7-22 Monteverde Institute 7-8 Centro de Artes 9-13 Friends School, Monteverde 14-15 El Colegio, Santa Elena 16-17 Patricia Jimenez 18-20 Wendy Rockwell 21-23 PART III Â– Conclusions 24-25 What Seems to Work 24 What Seems Not to Work 24 The Future of Gray Water in Monteverde, CR 25 Imporant Contact Information 26 APPENDIX Â– R EED b ED M AINTANENCE M ANUAL A-1 Â– A-7 Detachable Manual for Maintainin g a Gray Water Reedbed: A-1 Â– A-7
R b MM Â– 2 PART I Â– Introduction The mountain town of Monteverde is widely recognized for its cloud forest reserves and scenic beauty. The communi ty has experienced massive growth in tourism over the last two decades (CW3). While ther e are positive aspects of this growth, including job creation and economic diversification (a3), the associated environmental impact has been considerable (CW2, CW3). Specifically, the demand for clean water as well as the volume of wastewater has grown significantly (a8). The increased water use has created a visible and malodorous wastewater pr oblem, especially in the denser population areas. Wastewater can be divided into two main categories: greywater and blackwater. The latter comes from a toilet and contains urine and feces. In Costa Rica, this is captured in a septic tank Greywater comes from sinks, laundries and showers and generally goes directly on to the ground without any treatment. One, low technology, low cost type of greywater treatment system that has been introduced in Monteverde is a construc ted wetland. Because constructed wetlands are modeled after natural system s, using roots and plant physiology, they are called biological or Â“living syst emsÂ”. These biologic al systems eliminate the pollution of surface and groundwater, capturing the valuable nutrients for reuse (for example, agricultural irrigat ion), thereby reducing the demand for fresh water (CAC6). A constructed reedbed consists of a plastic-lined trench planted with a local species of reed grown Â‘hydroponi callyÂ’, e.g. with no so il in the trench, only water and crushed rock. The greywater provides all the nutrients required for the reeds to grow. From exiting the household to exiting the reedbed, the water flows completely below the surface, elim inating odor and health problems. After the greywater has passed through t he reedbed and most of the nutrients removed, it may flow into a small pond where sunlight, aeration, and certain water plants or fish can further improv e the water quality. The treated water finally flows into a soakage basin (abs orption trench) planted with water-loving plants. There are nine constructed wetlands /reedbeds in the Monteverde area. Most of these were built due to the initia tive of Stewart Dall as, a Ph.D. candidate from Murdoch University, Australia, who worked as a research associate with the Monteverde Institute from 1999Â–2003. Five of the existi ng wetlands in the area are on public property (permission to invest igate may be required, from a school for example) and four are on private land (permission to investigate is definitely required). Listed in order of ease of accessibility: Public: Community Arts Center, Montever de Institute, Friends School, the Colegio de Santa Elena Private :The Monteverde Institute DirectorÂ’ s house, the Centro de Educacion Creativa DirectorÂ’s house, W endy RockwellÂ’s, Patricia Jimenez and Gary DillerÂ’s. Almost all of the current insta llations are not being maintained or monitored appropriately. Purpose:
R b MM Â– 3 The purpose of writing this manual is threefold: to doc ument the reedbeds in the local area, to improve maint enance, and to promote water treatment education. The authors hope that the m anual will prove useful to both reedbed owners and future volunteers in the main tenance and construction of existing and new reedbeds. Ideally, we would like to see every existing reedbed functioning properly and maintained over time. In wr iting this document, we hope to provide continuity between past, present, and future volunteer work. We hope that local reedbeds may serve as wastewater envir onmental education tools for local and international students. Additionall y, the final appendix (the Reedbed Maintenance Checklist) may be deta ched and used independently for reedbed maintenance and troubleshooting.
R b MM Â– 4 MAPS Figure 2. Topographic Map of the Montev erde Zone. Reedbed sites are designated by red circles: 1) the Friends School, 2) the Centro de Arte Creativo, 3) the Monteverde Institute, 4) the house behind the Monteverde Institute, 5) Wendy Rockwell and Jim StanleyÂ’s house, 6) Patricia JimenezÂ’s house, and the 7) the Colegio de Santa Elena. Figure 1. Locator Map of Monteverde, Costa Rica.
R b MM Â– 5 Basics of Reedbeds Figure 3. Constructed wetland systems (often referred to as Â‘reedbedÂ’ for the hydroponic, root filtration trench) are a low-cost, low-technology approach to treating greywater. In general, the flowpath of greywater through the wetland directs water first through a grease trap to separate solids and then into the reedbed itself, entering through a slotted bucket that forces water to enter at root level. The greywater should at least meet U.S. standards for irrigation water after passing through the primary reedbed. The filtered water can enter the soil via another reedbed (next page, top), an absorption trench (next page, middle), or an aeration pond (next page, bottom), or the water could simply seep into the ground. The filtered water may also be used to water gardens or crops. Key:
R b MM Â– 6 Â“Kit of PartsÂ”
R b MM Â– 7 PART II Â– Case Studies Monteverde Institute Reedbed Figure 4. Diagram of the greywater flow path through the reedbed at the Monteverde Insitute The Monteverde Institute reedbed was c onstructed in 2002 (?) by Stewart Dallas. Ignacio, the physical plant staff at the Institute, now oversees upkeep and maintenance of the reedbed, making it the best-maintained reedbed system in the area. Ignacio (a.k.a. Â“NachoÂ”) trim s back the JobÂ’s Tears to a height of one foot at the beginning of every dry seas on, as well as fixing any problems on an as-needed basis. The Institute reedbed system covers a large surface area, wrapping about halfway around the Institute. Greywater flows into two adjacent grease traps, through a solid-filtration bed into the r eedbed itself. A secondary reedbed, used seasonally, connects the reedbed to the drainage ditch. Greywater flows both from the kitchen and bathroom sinks and fr om the lab sinks to adjacent grease traps, where grease and food scraps settl e out. The greywater then flows through a lined trench filled with large rocks to remove any remaining large debris. There is a viewing pipe (3Â” PVC tube with a cap) for maintenance purposes, i.e. ensuring that water is st ill flowing through t he path. Next, the greywater enters the primary reedbed, e.g. the large, lined trench that has JobÂ’s Tears growing hydroponically on the surface of the gravel. From here, there is
R b MM Â– 8 an additional flow path, only connected durin g the rainy season, which supports a host of aloe plants, as aloe is more dr ought-tolerant. During the dry season, the treated greywater moves directly from t he primary reedbed to the drainage basin. During the rainy season, the drainage bas in becomes a pond, which Ignacio reports as occasionally ov erflowing onto the road. The Institute reedbed has had probl ems, which have been addressed quickly by Ignacio. In 2004, alerted by a foul odor, he dug up the first trench to discover that the lining was blocking the inlet pipe from the grease trap, preventing water from enteri ng the solid filtration bed. Figure 5. Photograph of the Monteverde Instit ute reedbed, showing the flow path of greywater from the grease traps through the secondary reedbed (flow path is depicted with a dashed red line).
R b MM Â– 9 Community Art Center Reedbed Figure 6. Photograph of the Cr eative Art Center reedbed in May 2005. The greywater flow path is shown with a dashed red line. The reedbed at the Community Art C enter was the first installed by Stewart Dallas, in conjunction with hi s Ph.D. research affiliated with the Monteverde Institute. The goal of the system was Â“to demonstrate an inexpensive sanitation syst em for greywater that is easy to maintain, that conserves freshwater resource s, and is open to the public.Â” The reedbed was constructed in 2000 and represented a l earning experience both for Stewart and the Monteverde community in the installa tion of constructed wetlands to treat greywater. Restoring this reedbed, which had fallen into severe disrepair after StewartÂ’s departure in 2003, has been the main focus of the authorsÂ’ efforts from February to June 2005. The spirit of our restoration has been in keeping with the original installation: to use the reedbed as a learning experience, turning it into an educational tool for local and visiting students, community members, and interested tourists. Students from 5th through 11th grade, from both Monteverde and the U.S., have been involved in vari ous steps of the restoration from beginning to end.
R b MM Â– 10 Figure 7. Diagram of the curr ent design of the CAC reedbed. The Original CAC Reedbed Design: Initially, the inlet to the reedbed was supposed to combine greywater from the bathroom sink, the kitchen sink, the ce ramic studio sink and blackwater from the composting toilet. However, the blackwater was not connected due to health concerns, and the sink from the cerami c studio was deemed to have too much clay. The reedbed itself is a lined plasti c trench with dimensions of 7.2 m x 1.3 m x 0.6 m. These dimensions were a func tion of available space, volume of greywater and volume of rain. It is a submerged flow reedbed that includes an internal baffle of 10 meters in length that the water must travel around before it flows out of the reedbed. To reduce cost s, cut-up, non-recyclable plastic bottles were used instead of gravel as a subs trate on which the plants roots could stabilize. A thin layer of stone was put over the bottles. The treated greywater then entered an aeration pond, which over flowed into an absorption trench. Water from the ceramic studio sink was directed into a bathtub, located adjacent to the far end of the filtration bed, to act as a sediment settlement tank. Ideally, after the clay separated out, the water would enter the reedbed. However, the settled clay clogged the bathtub drain, and the water backed up within the tub. Perhaps for this reason, the excess water was rerouted directly to the absorption trench. In the center of the aeration pond stood a large tractor tire filled with gingerlilies. Water lilies, dragonfly larvae, and fish lived in the water. The pond provided Â“aesthetics and as a simple visu al demonstration to visitors of the
R b MM Â– 11 systemÂ’s performance.Â” Overflow from t he pond spilled into an absorption trench planted with Xanthesoma and banana trees. To help visitors understand the conc ept of treating greywater with a constructed wetland, a large mural depicting each step was painted on the outside wall of the ceramic studio, just over the reedbed. While the mural does not accurately reflect the situation at t he Arts Center (for example, it shows shower and laundry water going into the Constructed Wetland although the Center has neither), it can be used appr opriately from an educational extension point of view. Reedbed Condition in February 2005: Through a complete lack of maintenance between 2003 and 2005, the entire wetland system was in a stat e of considerable disrepair. Weeds (invasive or non-native plants) had overgr own the reedbed, the adjacent retaining wall, and the pond. The education mural wa s covered in dirt and waspsÂ’ nests. The path between the reedbed and the pond was muddy, slippery and presented a potential hazard to anyone walking dur ing the rainy or windy seasons. In an instance of misguided attempted maintenance, the pipe from the grease trap (the main inlet pipe into the reedbed), had been moved to discharge approximately a foot over the surface of t he reedbed, eliminating the element of subsurface flow and preventi ng the greywater from entering at root level. The reedbed itself was an eyesore. JobÂ’ s tears grew mainly near the inlet pipe, with gingerlilies growi ng over the center. Inva sive and non-native species were sprouting up everywhere, competing with the juvenile JobÂ’s Tears. An Apricot Moon Tree, a non-native species fr om South America, had grown in one of the tires in the retain ing wall, shading the far si de of the reedbed and possibly the reason few adult JobÂ’s Tears were gr owing at that end. Decaying organic matter had formed a layer of soil approximat ely 2 inches thick. However, the roots from the adult JobÂ’s Tears had penetrated below the water level and had expanded to fill the available space between the plastic bottle pieces. The water in the aeration pond was stagnating and too low to overflow into the absorption trench, both because the water level dropped during the dry season, but also due to holes in the pond liner. T he pond was overgrown with weeds and had become a nursery for mosquito larvae. Field Work February 2005 June 2005: The authors, with the hel p of students from Suns et Middle School in Colorado, CEC 5th graders, and the CEC high school water mini-class, all donated many hours of work to the restor ation of the CAC r eedbed. Over the course of four months, we transformed the wetland into an educational tool for the community. We began by cleaning up the area: removing the old trellis, washing the mural and windows, placing flat stones into the footpath, and
R b MM Â– 12 fashioning a bridge over the flow path fr om the primary to the pond. We also made more fundamental, structural changes. One of the major changes we made wa s to replace the old bathtub, which had been the clay settlement tank, and tran sform it into a germination bed for new wetland plants. The greywater from the ceramic studio had been directed to the bathtub, which was supposed to act as a sediment trap to separate out the clay before it entered the reedbed. Ho wever, the bathtub effluent had been directed into the forest instead of into the reedbed, as designed. We replaced the bathtub with a 55-gall on blue plastic drum, along with a Wendy Rockwellstyle exit valve to clean the clay sedim ent out every so oft en. Flushing the drum is simple, as the exit valve is easily a ccessible with a space for a bucket to collect the clay waste for proper disposal or dr ying/reuse. We mov ed the old bathtub to the forest edge adjacent to the absorption tr ench and filled it with large and small rock-shaped pieces of concrete that had been underneath it to supp ort it upright. Real rocks and bricks from the same source were used to line the adjacent storm drainage ditch. The bathtub was then co vered in dirt recovered when the hole was dug in the former bathtub site for the new 55 gallon blue barrel. Thus, a germination bed was created ut ilizing the old bathtub and now contains juvenile JobÂ’s Tears grown from seed. Finally, after much debate, we decided to remove the pond and replace it with a secondary reedbed. The pond was no longer aesthetically pleasing, and it had become a mosquito br eeding habitat, presenting a danger to small children. We tran splanted the viable native r eeds growing in the pond to the reedbed, where they are now thriving. We moved or disposed of the tire, weeds, and the broken plastic liners. Usi ng funds from the Fulbright program, we lined the hole from the pond with dirt and th en new plastic liners. We secured the edge of the lining with large stones, which also serve to protect the reedbed from visitorsÂ’ and dogsÂ’ feet. We filled t he lined hole with unglazed clay pottery shards, plastic bottles pieces, and gravel Finally, we transplanted the juvenile JobÂ’s Tears from the new germination bed onto the gravel surface. The secondary reedbed now connects the primary reedbed and the absorption trench, and the entire wetland is a fully functional system. The CAC reedbed as a wetland plant nursery: We consulted with local botanist Willow Zuchowski to determine which plants are native to a local natural we tland in order to try to transplant or grow from seed new plants to try in the CAC reedbed. We hope to use that reedbed as a nursery to grow water-toler ant plants other t han JobÂ’s tears for other local reedbeds. Increased variety of plants in a reedbed would not only increase the aesthetic value, but provi de plants with various root depths to maximize water uptake throughout the changing seasons. Through Willow, we were able to ident ify several new, native plants to try to grow in the CAC reedbed. We transplanted several native Xanthesoma (elephant ear) plants alongside the semi-native Xanthesoma already growing in the absorption trench; about half of which survived. Next, two small Cyperacae (fam.) Carex (genus) sedges were transplanted successfully into the reedbed.
R b MM Â– 13 We also scattered sedge seeds directly into the reedbed, but new plants from seed have yet to show. We then transpl anted a second, drier, smaller sedge, Unsynia hamata into the reedbed, where it is th riving. This sedge might also grow well on the retaining wall sl ope. Additionally, we thought Laciasis, a Japanese-looking grass with bl ack fruits attractive to birds, would be a good candidate. We planted dozens of cutti ngs in the absorption trench and on the slope on the far side of the blue drum. Ho wever, these did not seem to take, and no new plants have come up. Finally, we attempted to transplant mint to the retaining wall slope, but they did not take. Willow also suggested that, in the future, Boccenia frutesin (which is described in her book) may be a good potential candidate for the absorption trench, as the fruit is a ttractive to birds. A dditionally, she recommended the rattlesnake plant ( Merantacae Calathae crotylyphera ) as a good candidate for the reedbed. Current Design: Water enters the primary reedbed fr om two locations: 1) from the ceramic studio sink, and 2) from all other gray water sources in the art center. Greywater from the kitchen and bath room sinks collect in one pipe that flows into a grease trap. The grease tr ap consists of a 5-gallon plastic bucket without a bottom; instead, ther e are large pottery shards over built-up grease. Most of the greywater passes through the grease trap directly into the reedbed, as the built up grease on the pottery shar ds prevents the greywater from passing into the ground before and under the reedbed The outlet from this trap becomes the main inlet pipe into the reedbed, entering into a closed, slottedbottom bucket to ensure that the water ent ers both below the surface level and at root level. The studio sink exits the buildi ng and enters the blue barrel in the foreground, which acts as a sediment trap to separate out suspended clay. Ostensibly, clay particles settle at the bottom of the barrel, while relatively sediment-free water rises to the top and is fed into the reedbed through a pipe the directs the greywater to the bottom of the reedbed. After the water passes through t he primary reedbed, it is directed into a trough that leads to a secondary reed-bed (top of above image). After the water passes through the secondary reedbed, an overflow trench directs it into the absorption trench.
R b MM Â– 14 Monteverde Friends School Reedbed (a) Figure 8 a,b. (a) Diagram of the Friends School reedbed. The flow path is marked on the photo (b) with a dashed red line. According to Friends School Director Jenny Rowe, this reedbed was installed in 2002 by Orlando Reyes fo llowing emailed in structions from Stewart Dallas. School Board Dire ctor Katy VanDusen served as the construction coordinator. The reedbed is now maintained by Ignacio and Alvaro (b)
R b MM Â– 15 Salazar, the maintenance men at t he Monteverde Instit ute and the Friends School respectively. Greywater exits from the kitchen and bathroom sinks and enters a grease trap, concealed under a panel in the concrete walkway at the head of the reedbed. Water enters the reedbed in a s ubsurface pipe and flows through the filtration bed. The JobÂ’s Tears appear to have been maintained (i.e. cut back for the dry season), but the ones at the top end of the reedbed were doing much better than those at the lower end. T he gravel surface also appears to have been maintained, having very little accumu lation of soil. Water also exits the reedbed below the ground and no exit pi pe or trench is visible. However, there are design flaws t hat make more in-depth maintenance difficult. First, there is no viewing pipe to check the inte rnal water level. Second, although the flow path is and should be comp letely subsurface, there is no visible inlet or outlet and, thus, no easily accessibl e sampling points. The inlet can only be accessed through removable panels on t he concrete walkway. However, when the authors attempted to remove the panels without a crowbar, we began to destroy the concrete. Finally, it is possible that the slope may be too severe to allow water to hold in the reedbed proper ly. The authors were unable to reach a conclusion, however, without being able to determine if the bottom of the reedbed trench is level or not. In either case, it may have been better to build the reedbed across the slope, perhaps further down t he slope to allow access to the courtyard by students while still re ceiving sufficient sunlight. During the craft fair of Christmas 2004, shoppers were distracted by an unpleasant, Â“sewageÂ”-like odor. According to Tim Sales, Ignacio opened the access panels and fixed the problem by Â“switching some tubing that had been installed incorrectlyÂ”. This assessm ent seems suspect, however, as the reedbed had been working fine (a.k.a. not produc ing an unpleasant odor) for two years previously. Also, when we attempted to lift the access panel by unsealing the central bolt, a distinctly unpleasant, sewage-lik e odor drifted up. Therefore, it is possible that any foul odors disturbing t he craft fair were coming from the trap itself, and that the trap, not the tubing, may not have been functioning properly. We suggest that Alvaro or Nacho open the access panels to check for blockage. It is possible that the grease trap has never been cl eaned out and may be full. Additional future improvements could include: insert a viewing pipe, putting up educational signs, and making pi pe access easier for maintenance and sampling. In any or all of these steps it might be fruitful to involve students and teachers from the school both to increase wastew ater treatment education and to emphasize the importance of environmental maintenance. El Colegio de Santa Elena Reedbed
R b MM Â– 16 Figure 9a,b. Diagrams of the reedbed at the Col egio de Santa Elena. The flowpath is shown in a red, dashed line. (b) (a)
R b MM Â– 17 The reedbed at the Colegio de Sant a Elena was constructed in 2003 (?) under the supervision of Stewart Dall as. The reedbed system consists of a grease trap and one, 7m x 1m, filtration bed. From t he kitchen, the greywater and food waste goes into the original co nnection box and then into a second connection box, installed by Stew with t he help of students to give them an installation experience. T he greywater then flows into the most sophisticated grease trap we have observed thus far. The grease trap consists of a large (p robably 55 gallon) concrete barrel. The inlet pipe is located on the uphill side, about 4 inches higher than the outlet pipe on the downhill side. However, both t he inlet and outlet pipes are protected by a large T-valve. Thus, the level of t he water eventually rises to the height of the outlet pipe, but the incoming greywa ter is forced below the surface through the bottom of the entry T-valve. Ther efore, any heavy sus pended foods will sink to the bottom, and the grease wil l float to the surface. As the grease will not sink far enough to enter the bottom of the T-va lve on the outlet pipe, the outlet is protected from both food and grease, so onl y greywater exits the trap and enters the reedbed. There is also a Wendy Rockwe ll-style exit valve to flush the grease trap. However, the trap has never been flushed and no exit pipe is connected to the valve. The exit pipe t heoretically would extend to the far side of the reedbed, where the grease could either empty ont o the ground, or into a bucket which would collect the grease, allowing for its pr oper disposal in a solid waste disposal or its use as pig feed. Patricia Jimenez and Gary DillerÂ’s Reedbed
R b MM Â– 18 Figure 10. Diagram of the reedbed at Patricia a nd GaryÂ’s. A single sediment tank originally collected the greywater from the three neighbor ing houses before connecting to thegreywater from Patricia and GaryÂ’s grease trap. Howeve r, these houses are no longer connected and are not depicted here. Patricia and GaryÂ’s reedbed was construc ted in 2001 by Stewart Dallas as a case study for part of his dissertation research through Murdoch University (Australia). The details and results of this study have been published (Dallas 2004a, Dallas 2004b). This study marked the first time an environmental services contract for greywater trea tment had ever been signed in Costa Rica. Originally, the greywater from Patric iaÂ’s sinks and washing machine, along with the greywater from her three closest neighbors, was treated through a double filtration bed-to-aerat ion pond system. PatriciaÂ’s house had a separate, simple grease trap to filter out food and fa t before the water was piped to the first reedbed. The other three houses shared a grease trap/settling tank (both words are used to refer to the same device). The water entered the first reedbed at root-level through an inlet bucket. Stewar t (Dallas 2004b) descr ibed the reedbed design:
R b MM Â– 19 The rst reedbed is 14 m long, 1.2 m wide and 0.6 m deep (17 m2) and the second approximately oval in shape 6 m 3 m and 0.6 m deep (13 m2). The sec ond reedbed has internal plastic baf e walls to extend the ow path to approximately 12 m. The locally avail able crushed rock (nominal 20 mm) was determined to have a porosity of 40% which allowed an effective total storage volume of 6 m3 (6000 l) or 2.4 days minimum hydraulic retention time (HRT)Â…. After passing through the reedbeds, the treated grey-water ows into a shallow Â‘polishingÂ’ pond (approximately 2.5 m3) containing sh (tilapia and minnows to consume any mosquito larvae, in addition to several aquatic plant species including water hyacinth ( Eichornia crassipes ), water lettuce ( Pistia stratiotis ) and local Â‘ patita Â’ ( Heteranthera reniformis ). Figure 11. The primary reedbed at the Jimenez/Diller house.
R b MM Â– 20 The reedbed installation began in Febr uary 2001 and continued over the next 6 months, gradually connecting one house at a time, in order to allow the plants to mature. For the first two years after installation, the reedbed functioned well. Stewart Dallas and Brian Scheffe visited r egularly to monitor BOD, turbidity, and fecal coliform levels in the effluent. However, after about two years, t here began to be problems with flow through the reedbed, indicated by overflow from the grease trap. Patricia hypothesized the cause was that greywa ter was not flowing quickly enough through the reedbed. She also stated t hat, although she believes the grease trap should be emptied every six months, it has not yet been done. Dallas (2004b) reported that 30% of the second r eedbed became barren and hypothesized the cause to be either too much shade or too lit tle nitrogen in the wa ter. Although it is recommended that reedbeds be located in extremely sunny areas, keeping the trees in their yard was and is very impor tant to Patricia and Gary, and excessive shade may indeed have turned out to be a problem in the long run. Eventually, after Stewart returned to Australia in September 2003, there ceased to be any treated greywater flowi ng out of the reedbed at all, possibly because the reedbed became blocked or because of a hole in the plastic lining. Leaves from the nearby trees, leaves from the JobÂ’s Tears, and soil eroding from the adjacent slopes have built up on the surface of the reedbed, and may have contributed to the clogging. The pond is now dry and abandoned. PatriciaÂ’s son, Jeremy, attempted to dig up the gravel and search for a hole, but was ultimately unsuccessful, due to the strenuous manual labor involved. Now, PatriciaÂ’s greywater flows unt reated back into the street again. Works Cited: Dallas, S., Ho, G., and Mathewa, K. (2004a) The Development and Operation of Low-cost Reedbeds for Greywate r Treatment in Costa Rica, Central America. WAMDEC Dallas, S., Scheffe, B., and Ho, G. (2004b) Reedbeds for greywater treatmentÂ—case study in Santa Elena -Monteverde, Costa Rica, Central America. Ecological Engineering 23 pp. 55Â–61 Wendy RockwellÂ’s Reedbeds
R b MM Â– 21 Wendy Rockwell and Jim Stanley live on t he left past Nidia Lodge on the way to the Butterfly Garden. Figure 12. Diagram of both reedbeds on Wendy RockwellÂ’s property. The upper reedbed (located at the side of the house) is five years old and receives its greywater solely from the kitchen sink. The lower reedbed (located behind the house) is two years old and receives greywater from the laundry sink and grey and blackwater from the new guesthouse. There are two reedbeds on WendyÂ’s property, one five and one two years old. She designed and super vised the construction of bo th herself, with advice in absentia from Stew. Both reedbeds have a surface area of approximately 6-7 m2. Water from the kitchen sink is treat ed by the older reedbed, while water from the outside sink, washing machine, and new casita is treated by the newer reedbed. Wendy has recently rerouted the piping to include blackwater from the new casita in the newer reedbed as well. Water from the kitchen sink flows to the five year old reedbed in the side yard (the upper of the two reedbeds shown in the above diagram) through a grease trap with an interesting and unique de sign. The trap is comprised of the standard 5 gallon bucket with an inlet pipe in stalled slightly higher than the outlet pipe. The entrance to the outlet pipe is pr otected by a fine wire mesh screen. However, at the bottom of t he side of the bucket, there is an alternative effluent pipe: a valve that normally remains cl osed but can flush t he contents of the bucket in order to clean it out. However, this exit valve discharges no more that
R b MM Â– 22 15 ft away, very close to the yard. T hus, the extra grease ends up piling up on the surface of the grass under some brush. Wendy ope ns the valve and flushes the grease trap once a week, and never has problems with clogging. However, this still leaves grease on the surface of the ground; perhaps at some point the grease could be rerouted into the septic tank. The greywater then moves through the wir e mesh screen into the filtration bed. The filtration bed is made of cutup bottles, covered over with a layer of gravel. The surface of the gravel is co vered in soil, probably derived from five years of uncleared, deca ying organic matter. There is no visible effluent. The outle t pipe may be too high, or there not may not be enough water entering the reedbed. ItÂ’s also possible that there is a hole in the reedbed below the level of the outlet pipe. The best solution to this would be to dig up the gravel and bottl es and replace the liner. The plants, however, looked healthy, if a little dry, for the height of the dry season, so the roots must deriving nutri ents from contact with the greywater. There are two reedbeds on WendyÂ’s property, one five and one two years old. She designed and supervised the construction of both her self, with advice in absentia from Stew. Both reedbeds have a surface area of approximately 6-7 m2. Water from the kitchen sink is treated by the older reedbed, while water from the outside sink, washing machine, and new casita is treated by the newer reedbed. Wendy has recently rerouted the piping to include blackwater from the new casita in the newer reedbed as well. Water from the kitchen sink flows to the five year old reedbed in the side yard (the upper of the two reedbeds shown in the above diagram) through a grease trap with an interesting and unique de sign. The trap is comprised of the standard 5 gallon bucket with an inlet pipe in stalled slightly higher than the outlet pipe. The entrance to the outlet pipe is protected by a fine wire mesh screen. However, at the bottom of t he side of the bucket, there is an alternative effluent pipe: a valve that normally remains cl osed but can flush t he contents of the bucket in order to clean it out. However, this exit valve discharges no more that 15 ft away, very close to the yard. T hus, the extra grease ends up piling up on the surface of the grass under some brush. Wendy ope ns the valve and flushes the grease trap once a week, and never has problems with clogging. However, this still leaves grease on the surface of the ground; perhaps at some point the grease could be rerouted into the septic tank. The greywater then moves through the wir e mesh screen into the filtration bed. The filtration bed is made of cutup bottles, covered over with a layer of gravel. The surface of the gravel is co vered in soil, probably derived from five years of uncleared, deca ying organic matter. There is no visible effluent. The outle t pipe may be too high, or there may not be enough water entering the reedbed. ItÂ’s also possible that there is a hole in the reedbed below the level of the outle t pipe. The best solution to this would be to dig up the gravel and bottles and r eplace the liner. The plants, however, looked healthy, if a little dr y, for the height of the dry season, so the roots must derive nutrients from contac t with the greywater.
R b MM Â– 23 The newer, two year old reedbed is located behind the house. The laundry/outdoor sink empties into this r eedbed, as does the gr eywater from the newly built guesthouse. Wendy and Ji m have just recently begun to add blackwater from the new gues t house as well. The plant density in this reedbed is quite low (heavier on the end, almost nothing in the middle). Approximately 3 m2 total is covered with JobÂ’s Tears. This reedbed is unique in t hat it is made of mesh bags filled with cut-up bottles, cover ed over with a thin layer of gravel. The effluent from this reedbed is visible but smelly. The effluent flows into an aeration pond instead of an abs orption trench, so that the odor is not only unpleasant, but irritating. We suspect that the outlet pipe is so much higher than the water level in the reedbed that the ret ention time during the dry season is too long. Also, we observed, at least in t he middle of the reedbed, that the root level penetrates the mesh bags in order to in teract with the greywater during the dry season. We suggested to Wendy that s he add more water during the dry season to raise the water level and/or lower the le vel of the outlet pipe. Additional ideas for improving the reedbed include conv erting the pond to an absorption trench and cutting holes in the mesh bags and scatte r the bottles to allow the roots to penetrate lower. Part IIIÂ—General Conclusions: What Seems to Work Best: In our observations of the construct ed wetlands in the area, the authors recommend the following techniques: Using the T-valve grease trap design, being sure to flush it regularly
R b MM Â– 24 Ensuring that the JobÂ’s Tears that receive plenty of sunlight and an appropriate volume of greywater. Cutting back the JobÂ’s Tears to a height of 30 cm at the onset of the dry season every year. The addition of other wetland plants with a variety of root depths. This has the added bonus of being more aesthetically pleasing. For the reedbed filling, we recomm end using a mixture of cut-up plastic bottles and gravel. This drastically r educes the construction cost, as well as reducing the weight of the ree dbed. The reduced weight makes it easier to dig up if necessary and reduces the pressure on the plastic liner. Adding blackwater to the reedbed. Th is acts as fertilizer to the JobÂ’s Tears, keeping them healthy and growing. Regularly cleaning the surface of t he gravel, to remove leaf litter and decaying organic matter. What DoesnÂ’t Seem to Work Well: Likewise, the authors discourage the use of the following: Small grease traps or greas e traps with no T-valve. Not cleaning the grease trap. Grease traps and inlet valves that are not easily accessible, as this makes maintenance and troubleshoot ing very difficult. Enclosing the cut-up plastic bottles in mesh bags. This prevents the JobÂ’s Tears roots from penetrating to the nec essary depth to properly interact with the greywater. Building an aeration pond. Unless regularly maintained, these ponds can quickly turn into stagnating pools that at tract mosquito larvae and bacteria. Additionally, unless protec ted by a low fence, they are constantly at risk from the nails of small animals drawn to drink there, as well as presenting a danger to small children. Building the reedbed on a slope. At l east the bottom of the trench needs to be built on the level. However, even if the base is level, if the surface of the reedbed slopes, the outlet pipe wil l be too low and the water will pass through too quickly. If the only site available for building is located on a hill, the trench should be dug perpendicular to the slope. Closing Remarks: Greywater generally goes untreated in Latin America. Finding low technology, low-cost methods of treating greywater is necessary for health and aesthetic reasons. Where such solutions are applied, water treatment education and an emphasis on maintenance are key to maintaining those systems. Costa Rica has been called a Â‘low maintenance cult ure.Â’ For a water treatment system to be successful here, a low-maintenanc e method or the de signation of a committed individual or group to be responsib le for all maintenance is absolutely
R b MM Â– 25 necessary. Patricia Jimenez has suggest ed the idea that ther e may be a cap on the lifetime of a reedbed. Even with proper maintenance, it is possible that a reedbed may need to be dug up and re-done ev ery so many years because of rain, wind and dust. Patricia stated that she Â“has no doubt that the reedbed will work. But, does it need to be redone ever y 2 years? Or 3? Or 4?Â” Whether or not that is true of all re edbeds, it is certainly true of some of the existing reedbeds. Thus, we conclude that reedbeds are only an appropriate solution for greywater treatment for individual households in which the members are committed to the maintenance of the r eedbed, meaning that the time and money to upkeep the system is available. For larger groups or publ ic systems, a large reedbed or series of reedbeds probably r equires too much time and labor to maintain without a paid staff. As the transient and permanent populat ions of Monteverde increase, its citizens are beginning to be more c oncerned about the unsi ghtly appearance and odor of greywater in the st reets. The attitude of t he community may be currently favorable to the construction of neighb orhood greywater treat ment systems. However, as long as water is available in plenty and cheaply, the idea of paying for greywater treatment may not be well-re ceived. However, it is required by Costa Rican law that all households and bus inesses treat their greywater. In places where there is no general greywate r treatment system in place, however, that law is simply not enforced. Na t Scrimshaw, Director of the Monteverde Alliance, has suggested working with AyA to enforce penalties for non-treatment of greywater is such a system is in place and families in the neighborhood choose to refuse its services. Even if local residents would agree to pay a nominal monthly fee for greywater treat ment, however, the law does not require residents to contribute to the construction of a local greywater treatment system. Thus, outside funding would probably need to be found for the installation of such a system. Contact Information: Alvaro Salazar: Maintenance man at t he Monteverde Friends School, otherwise a local handyman who works out of his hom e in Bajo del Tigre. Home Phone: 645-5544 Dan Craig: Institute volunteer from Ma rch-June 2005, working on water treatment system repair and education. Dan is also an architect who lives in Denver, Colorado (USA). Email: firstname.lastname@example.org
R b MM Â– 26 Ignacio ________: Maintenance man at the Monteverde Institute, who also serves as the handyman at the Friends School in the absence of Alvaro. He can be contacted through a message at t he Monteverde Institute (645-5053). Jorge Monges: Agricultural teacher at the Colegio de S anta Elena, very knowledgeable about the r eedbed and other alternative technologies (e.g. the schoolÂ’s inactive biodigestor) Lindsay Stallcup: Ph.D. candidate at t he University of Georgia (USA) studying water quality and chemistry, also a 2005-2006 Fulbright Scholar and Research Affiliate with the Montever de Institute. Email: email@example.com Patricia Jimenez: Reedbed owner who liv es in Santa Elena behind the Tranquilo Internet (owned by her son, David). Phone: 645-5045. Email: firstname.lastname@example.org Scott Harlow: Volunteers annually fr om Oct.-May at the CEC and now the Monteverde Institute, t he best contact for general, current information or volunteer opportunities. Email: email@example.com Silvia Newell: 2004-2005 Research Affilia te at the Montev erde Institute and Fulbright Scholar. Ph.D. candidate at Princeton University (USA) studying aqueous geochemistry and molecu lar biology. Email: firstname.lastname@example.org Stewart Dallas: Ph.D. candidate (Defendi ng in 2005) at Murdoch University (Australia). Designed, inst alled and/or consulted on mo st of the local reedbeds. He or his publications are an excellent re source for historical information or techniques. Email: email@example.com Wendy Rockwell: Local reedbed owner in Cerro Plano. Has extensive connections with the Colegio, also on the Monteverde Dis trict Municipality Board. Phone: