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SUSTAINABLE WASTEWATER TREATMENT & REUSE

Tela, Honduras

SEEHD Sustainable Engineering and Environmental Health for Development

California State University, Chico

Final Draft

May 9, 2006

Prepared for

Municipalidad de Tela

Tela, Atlántida, Honduras C.A.

Sustainable Wastewater Treatment and Reuse - 2006

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ACKNOWLEDGMENTS SEEHD-Chico Contributors: Benjamin Fontana, Design

[email protected] Benjamin Forte, AutoCAD Drawings

[email protected]

David Ludwick, Contributing writer [email protected]

Sadie McEvoy, Contributing writer [email protected]

Scott Smith, Design [email protected] Report Editor: David Ludwick, [email protected] Faculty Advisor: Stewart Oakley, PhD., Contributing Writer [email protected]

Department of Civil Engineering California State University, Chico Municipality of Tela Collaborators: Marcos Yánes

Isabel Rivera


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TABLE OF CONTENTS ACKNOWLEDGMENTS............................................................................................................................ II

LIST OF TABLES.......................................................................................................................................VI

LIST OF FIGURES................................................................................................................................... VII

EXECUTIVE SUMMARY ......................................................................................................................VIII

OVERVIEW .............................................................................................................................................VIII

CONCLUSIONS AND RECOMMENDATIONS ........................................................................................ IX

Sludge Removal (To be done as soon as possible) .............................................................................. ix

Flow Measurement............................................................................................................................... ix

Effluent Reuse Pilot ............................................................................................................................. ix

INTRODUCTION ......................................................................................................................................... 1

PROJECT BACKGROUND......................................................................................................................... 1

Project Preparation: .............................................................................................................................. 1

Brief History of the Existing Treatment System:.................................................................................... 1

Problems to be Addressed: .................................................................................................................... 3

PROJECT ASSESSMENT TRIP ................................................................................................................ 4

Issues Addressed During Assessment Trip: ........................................................................................... 4

PROJECT OVERVIEW ............................................................................................................................... 5

DIVERSION OF INFLUENT TO SECONDARY LAGOON................................................................... 5

BYPASS OPTION #1: CONCRETE RECTANGULAR OPEN CHANNEL ............................................. 6

Calculations: .......................................................................................................................................... 7

Design Dimension for Concrete Square Channel: ................................................................................ 8

Recommended Construction Procedures:.............................................................................................. 8

Concrete Channel Cost: ......................................................................................................................... 9

BYPASS OPTION #2: CIRCULAR PLASTIC PIPE ............................................................................. 9

Calculations: ........................................................................................................................................ 10

Recommended Construction Procedures:............................................................................................ 10

Pipeline Cost:....................................................................................................................................... 11

BYPASS OPTION #3: REINFORCED BLOCK OPEN CHANNEL ..................................................... 12


Reinforced Block Open Channel Cost: ................................................................................................ 13

COST COMPARISON .............................................................................................................................. 13


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REMOVAL OF SOLIDS IN PRIMARY LAGOON................................................................................ 14

SLUDGE REMOVAL REQUIREMENT .................................................................................................... 14

DRAINAGE AND DRYING OF PRIMARY LAGOON ............................................................................ 14

Cost of Drainage:................................................................................................................................. 15

SLUDGE REMOVAL AND DISPOSAL ................................................................................................... 16


Equipment: ........................................................................................................................................... 17

SLUDGE REMOVAL WORK TIME REQUIRED.................................................................................... 17

Calculations: ........................................................................................................................................ 17

COST OF SLUDGE REMOVAL ............................................................................................................... 18

Sludge Removal Cost Estimate: ........................................................................................................... 19

Total Sludge Removal Cost:................................................................................................................. 20

EXCESS SLUDGE STORAGE OPTIONS ............................................................................................... 20

FLOW MEASUREMENT .......................................................................................................................... 21

PARSHALL FLUMES ............................................................................................................................... 21

ANALYSIS OF EXISTING PARSHALL FLUME .................................................................................... 21

SIZING AND INSTALLATION OF PREFABRICATED PARSHALL FLUME ....................................... 22

Sizing:................................................................................................................................................... 22

Installation: .......................................................................................................................................... 23

Parshall Flume Cost: ........................................................................................................................... 23

EFFLUENT REUSE.................................................................................................................................... 24

PROPOSED PLAN FOR THE PILOT NURSERY................................................................................... 24

Existing Nursery Site: .......................................................................................................................... 24

Proposed Nursery Site: ........................................................................................................................ 25

Pilot Nursery Proposal: ....................................................................................................................... 25

EFFLUENT WATER QUALITY ............................................................................................................... 26

Microbiological Quality: ..................................................................................................................... 26

World Health Organization Guidelines: .............................................................................................. 27

Physical-Chemical Quality: ................................................................................................................. 29

Evaluation of Water Quality Guidelines for Irrigation ....................................................................... 29

DESIGN OF EFFLUENT DELIVERY TO NURSERY SITE ................................................................... 30

Design Criteria: ................................................................................................................................... 31

Calculations: ........................................................................................................................................ 32


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Cost of Effluent Delivery System: ........................................................................................................ 35

EFFLUENT REUSE FOR AQUACULTURE.......................................................................................... 36

EVALUATION OF WORLD HEALTH ORGANIZATION GUIDELINES FOR AQUACULTURE ......... 36

ESTIMATED TILAPIA PRODUCTION IN TERTIARY LAGOON ........................................................ 37

ESTIMATED COST AND BENEFIT OF ANNUAL TILAPIA PRODUCTION ...................................... 38

COMMUNITY SURVEY ........................................................................................................................... 39

COMMUNITY SURVEY BACKGROUND ................................................................................................ 39

SURVEY FEEDBACK AND LOCAL IMPACT ......................................................................................... 40

Knowledge and Opinion of Wastewater Treatment System:................................................................ 40

Opinion of Wastewater Reuse Projects: .............................................................................................. 41

Reported Impacts of the System: .......................................................................................................... 41

Reported Household Illnesses:............................................................................................................. 42

Domestic Practices Reported by Community: ..................................................................................... 42

CONCLUSIONS AND RECOMMENDATIONS .................................................................................... 43

DIVERSION CHANNEL .......................................................................................................................... 44

PRIMARY LAGOON DRAINAGE ........................................................................................................... 44

SLUDGE REMOVAL ................................................................................................................................ 44

FLOW MEASUREMENT .......................................................................................................................... 45

EFFLUENT REUSE .................................................................................................................................. 45

REFERENCES ............................................................................................................................................ 46

APPENDIX A............................................................................................................................................. A-1

AUTOCAD DRAWINGS ...................................................................................................................... A-1

TABLES AND GRAPHS: WORK PLAN FOR EFFLUENT DELIVERY............................................... A-5

TIMELINES AND WORK PLANS ...................................................................................................... A-10

COMMUNITY SURVEY AND INTERVIEW QUESTIONS ................................................................ A-12

PARSHALL FLUME PRICE QUOTE................................................................................................... A-13


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LIST OF TABLES Table 1: Concrete Channel Costs........................................................................................ 9 Table 2: Pipeline Cost....................................................................................................... 11 Table 3: Reinforced Block Open Channel ........................................................................ 13 Table 4: Cost of Primary Lagoon Drainage...................................................................... 15 Table 5: Sludge Removal Cost Estimate .......................................................................... 19 Table 6: Parshall Flume Flow Ranges .............................................................................. 22 Table 7: Parshall Flume Cost Estimate............................................................................. 23 Table 8: Removal of Fecal Coliforms and Helminth Eggs in Tela Lagoon System......... 27 Table 9: World Health Organization Recommendations,................................................. 28 Table 10: Physical-Chemical Water Quality Results for Tertiary Pond Effluent............. 29 Table 11: Siphon Flow Characteristics vs. Pipe Diameter ............................................... 35 Table 12: Estimated Cost of the Effluent Delivery System.............................................. 36 Table 13: Microbiological Criteria for the Aquacultural Use of Wastewater. ................. 37 Table 14: Pipe Diameter with Associated Flow and Head Loss..................................... A-5 Table 15: Pipe Diameter and Related Dead Load on Rio Hylan Bridge ........................ A-6 Table 16: Effluent Reuse Spreadsheet ............................................................................ A-8 Table 17: Effluent Reuse Sample Calculations .............................................................. A-9 Table 18: Iterative Procedure to Produce Friction Factor, f............................................ A-9 Table 19: 2006 Timeline and Work plan Schedule. ..................................................... A-10 Table 20: 2007 Timeline and Work plan Schedule. ..................................................... A-11


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LIST OF FIGURES Figure 1: Tela wastewater treatment system lagoon layout................................................ 2 Figure 2: Sludge surfacing and visible at the primary lagoon entrance.............................. 3 Figure 3: The proposed diversion channel alignment......................................................... 6 Figure 4: Proposed sludge storage area is visible in the background. .............................. 14 Figure 5: Typical excavator. Note the boom length is critical.......................................... 17 Figure 6: Potential onsite sludge storage locations........................................................... 20 Figure 7: The original Parshall flume built in 1994......................................................... 22 Figure 8: The most recent Parshall flume, built in 2004.................................................. 22 Figure 9: The existing nursery and setup that will be relocated. ...................................... 24 Figure 10:The proposed nursery site................................................................................. 25 Figure 11: The final treated effluent leaving the treatment system. ................................. 26 Figure 12: The proposed irrigation supply delivery plan................................................. 31 Figure 13: The Rio Hylan Bridge, facing north towards the treatment system. ............... 32


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EXECUTIVE SUMMARY Overview This report summarizes the findings of the Sustainable Wastewater Treatment and Reuse Project conducted by SEEHD (Sustainable Engineering and Environmental Health for Development) at California State University, Chico for the Municipality of Tela, Honduras. The purpose of this report is to provide the Municipality of Tela with a formal remediation and renovation plan for improving the condition and operation of the current wastewater stabilization pond system in order to make it sustainable over the long-term. SEEHD has undertaken a multi-disciplinary approach toward facility renovations and sustainable development and has developed technologically appropriate solutions to the problems facing Tela’s wastewater treatment system. If these problems are left unresolved they will cause system failure and an increased prevalence of water and excreta-related infections in the local community. It is our recommendation that the Municipality of Tela begin planning for the desludging of the primary lagoon as soon as possible, and for the implementation of the remainder of the project in spring and summer of 2007. SEEHD is committed to the success of this project and will work to assist the Municipality in securing funding from various aid organizations, as well as offering technical assistance in the implementation of the project.


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Conclusions and Recommendations The cost estimates required to successfully complete the project are summarized below:

Sludge Removal (To be done as soon as possible)

Cost Estimate Construction of a bypass channel for diverting influent flow to secondary lagoon. US $4,500 Draining and drying primary lagoon, assuming pumping is required. US $260 Removal of sludge from primary lagoon and onsite sludge burial. US $9,933 Total estimated cost for sludge removal: US $14,693

Flow Measurement

Cost Estimate Purchase and shipping of a prefabricated Parshall flume. US $2,000

Installation of Parshall flume, including material US $160 Total estimated cost for flow measurement: US $2,160

Effluent Reuse Pilot

Purchase of 60 m of 0.051m PVC pipe US $520

Extra material, supports and incidental labor US $533 Installation of pipe plus fittings US $66

Total estimated cost for effluent reuse transportation system: US $1,119 Total Estimated Project Cost: US $17,972


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INTRODUCTION

Project Background In the summer of 2005, SEEHD accepted the Sustainable Wastewater Treatment and Reuse project in Tela, Honduras. The project was originally proposed to SEEHD by the Municipality of Tela. During the course of the 2005-2006 academic year, California State University, Chico civil engineering students traveled to Tela for a site assessment trip. SEEHD worked with faculty and local engineers to develop this project report which includes the conclusions of our research and design and recommends a work plan for immediate implementation. Project Preparation: Student members of SEEHD prepared for the Tela project by completing a requisite course in environmental engineering and then enrolling in an elective design course addressing natural wastewater treatment systems. The latter course, offered by the faculty advisor, used the Tela treatment system as a case study and emphasized the unique conditions present in developing countries, including technical, environmental, cultural, and economic considerations. Additionally, the students communicated regularly with officials in Tela and consulted with professional engineers in Chico on the technical aspects of the project. With three Spanish-speaking team members, language barriers were not a concern to the team, although the students were required to research Honduran history and culture. Brief History of the Existing Treatment System: Tela’s wastewater stabilization pond treatment system (Figure 1) consists of a facultative pond, followed by two maturation ponds in series. The system, which was originally constructed as part of a US Agency for International Development (USAID-Honduras)


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project, has been in continuous operation for over 12 years. The system currently serves approximately 8,000 residents of Tela Vieja. Wastewater is pumped to the system from three pump stations that service various areas of Tela Vieja.

Figure 1: Tela wastewater treatment system lagoon layout.

In 2002, the Honduran environmental engineering consulting firm ECOMAC conducted a study of the system in Tela. The design and construction was funded by USAID-Honduras and constructed by a local contractor. The results of ECOMAC's study, which included operation data for the performance of the system, were presented in the report Informe de Monitoreo: Lagunas de Estabilizacion de Tela, Proyecto Monitorio de Sistemas de Estabilizacion de Tratamiento de Aguas Negras, (ECOMAC, 2004). These results are used throughout this report as the best available data on the operating performance and physical condition of the lagoon system.


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Problems to be Addressed: Tela’s wastewater treatment system currently requires several immediate improvements in order to prevent system abandonment, improve system operation, and to enhance long-term sustainability.

The first of the three ponds is a facultative lagoon, where the settled solids, or sludge, build up over time. Facultative lagoons generally require sludge removal every five to ten years. According to the ECOMAC report, approximately 3,000 m³ of sludge has accumulated since the system began operation. The sludge at the entrance to the primary lagoon has now reached a total depth of 4m and is visible at the surface. The surfacing sludge can be seen in the circled area in Figure 2 below. This is a definite indicator that sludge build up has reached critical volumes and must be removed as soon as possible or else the lagoon will have to be abandoned.

Figure 2: Sludge surfacing and visible at the primary lagoon entrance.

In addition to sludge accumulation, Tela’s wastewater treatment system lacks the ability to accurately measure influent flow rates. Due to a poor design, the system’s existing Parshall flume does not measure flow. A new Parshall flume is needed to enable flow


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measurement for the treatment system. It is important that the flume is correctly sized and installed for accurate flow measurement. Flow data will allow the Municipality to analyze system performance and to better plan for future maintenance and expansions of the system. Tela’s treated wastewater is a potential resource that can be reused. Several of the reuse alternatives explored have the potential to generate a small income for the municipality. This income could offset system operating costs and improve the systems sustainability. Project Assessment Trip In January 2006 five civil engineering students, accompanied by the faculty advisor and a graduate student of cultural anthropology, traveled to Tela for the project assessment trip. The purpose of the trip was to collect the data and information required for the advancement of the project. The trip also served as an opportunity for the team to view the site they had studied for six months and to meet their partners in Tela. Issues Addressed During Assessment Trip:

1. SEEHD visited the system site with the Assistant Director of Public Works, Marcos Yánes, to get a visual affirmation of the current condition of the system.

2. Measurements were taken of the existing flume. 3. System influent flow rates were measured. 4. A topographic survey was conducted along the proposed route of the bypass

channel, allowing SEEHD to draft AutoCAD drawings of the bypass grade and alignment.


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5. SEEHD held several meetings to discuss project ideas with public officials, including representatives from the Mayor’s office, Public Works, and other municipal agencies that work in the areas of environmental protection, agriculture, and social welfare.

PROJECT OVERVIEW

SEEHD has approached the design of this project in a sequential manner. The design report section of this report discusses the design and alternatives and well as cost estimate of each section. The design procedure has been broken into sections corresponding to the order in which the work must be done. The general design outline is as follows:

• Design alternatives for influent diversion around the primary lagoon from the system headworks to the entrance of the secondary lagoon, which allows for;

• Drainage of the primary lagoon and partial drying of the sludge, as well as; • Sludge removal and disposal, and • Implement flow measurement through installation of a properly sized and

calibrated prefabricated flume. The following sections elaborate on the above stages and design. UNITS: An attempt has been made to use exclusively metric units, however many construction materials are commonly referred to in US standard units and are done so accordingly in this report as appropriate.

DIVERSION OF INFLUENT TO SECONDARY LAGOON Before the process of draining and desludging the primary lagoon can begin, a bypass channel or pipe must be constructed to divert the system influent from the headworks at the primary lagoon to the secondary lagoon. The best route for this diversion is the west side of the primary lagoon, along the crown that separates the first and third ponds. The


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proposed route can be seen on the following page in Figure 3.

Figure 3: The proposed diversion channel alignment.

Construction of the bypass should begin as soon as possible, so that the primary lagoon may be drained in March-April of 2007. The sludge should be dried in-situ, during the months April-June, before it can be removed, as will be discussed later. Bypass Option #1: Concrete Rectangular Open Channel This option proposes that a rectangular open channel to divert the influent wastewater from the headworks to the secondary lagoon be constructed. The open channel will be constructed of concrete and will be along the existing berm crown that separates the primary lagoon from the tertiary lagoon as shown in Figure 3.


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Calculations:

Design Values:

, as measured onsite during visit , estimated

Manning Equation:

Assumptions:

Maximum flow, Qmax Manning Coefficient, n = 0.013 for concrete Slope, S = 0.005

Channel Depth = 0.5 m, Water Depth, D = 0.25 m

Channel Width, W = 0.5 m Calculations:

Hydraulic Radius, Rh = Area/Wetted Perimeter

170 L/s → Channel dimensions are suitable for


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design maximum flow Design Dimension for Concrete Square Channel: Interior Width = 0.5 m Interior Height = 0.5 m Recommended Construction Procedures:

1. Cut and fill designated section of crown in preparation for the channel construction. (Refer to page 2/4 of drawings, Appendix A-2).

2. Caution: A 0.5% or greater slope must be maintained along the alignment to assure sufficient flow and scouring velocity.

3. Construct/Install the proposed concrete channel with interior dimensions no less than 0.5 m x 0.5 m. Ideally, the flow will occupy only half of the constructed channel height at maximum flow. The remaining 0.25 m of freeboard depth is for occurrences of heavier than expected flow rates.

4. Insert a 0.46 m (18”) diameter PVC pipe, or equivalent, into the existing concrete headworks as shown on page 4/4 of plans, Appendix A-4. Run the length of pipe through the existing concrete wall to connect existing influent channel with bypass channel.

5. Allow the ability to shut off wastewater flow through the 18” pipe with use of a ball operated shut-off valve, cap and flange fitting, or other functional flow stopping device. This fitting will control flow of the wastewater between the headworks and the concrete diversion channel.

6. Construct the concrete channel per plan and in ordinance with local building techniques and operations.


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Concrete Channel Cost:

Table 1: Concrete Channel Costs

Item Unit Unit Cost (Lps.)

Quantity Sub-Total (Lps.)

Totala

(Lps.) Material

Concreteb m3 1,325 18.29 24,234 30,500 Miscellaneous Building Materials

10,000 10,000

Earthwork Excavation, by handb m3 80 25 2,000 2,519

Installation/ Construction

Laborb m 300 120 36,000 45,350 Total (Lps.) L. 88,369 Total ($US)c US $4,677 a. Inflation used if value was taken from March 2003 Boletín Estadístico. Inflation rate based on average

of 8% per year, (average of 2003, 2004, 2005 values of 7.7, 7.0, 9.2 respectively). Value calculated

using equation Price (2006) = Price (2003) *(1+0.08)(2006-2003)

b. Original construction prices taken from the Boletín Estadístico, Marzo 2003

c. Exchange rate of 18.895 Lps/$US, April 23, 2006

Sources: CIA, 2006; Boletín Estadístico, March 2003; Forex Capital Markets, 2003 Bypass Option #2: Circular Plastic Pipe This option proposes to construct a 0.45 m diameter pipeline that diverts the influent wastewater from the headworks to the secondary lagoon. This pipeline should be fully buried beneath the soil to protect the material from deteriorating sunlight.


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Calculations:

Design Values:

, as measured onsite during visit , estimated

Manning Equation:

for full pipe flow

Assumptions:

Manning Coefficient, n = 0.013 for plastic pipe Slope, S = 0.005

Calculations:

0.42 m → Use 18” Pipe

Recommended Construction Procedures:



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3. Insert a 0.46 m (18”) diameter PVC pipe or equivalent into the existing concrete headworks as shown on page 4/4 of plans, Appendix A-4.

4. Insert proposed fitting device equipped with ball operated shut-off valve, cap and flange fitting, or other functional flow stopping device.

5. Construct pipeline in sections and backfill as needed. Compaction of backfill is not necessary.

Pipeline Cost:

Table 2: Pipeline Cost



Totala

Material 18" Pipe b m 1,000 120 120,000 151,165 Pipe Fittings 4,000

Earthwork Excavation, by handb m3 80 25 2,000 2,519

Installation/ Construction Laborb m 100 120 12,000 15,117

Total (Lps.) L. 172,801 Total ($US)c US $9,145 a. Inflation used if value was taken from March 2003 Boletín Estadístico. Inflation rate based on average



b. Original construction prices taken from the Boletín Estadístico, Marzo 2003


Sources: Boletín Estadístico, 2003; CIA, 2006; Forex Capital Markets, 2003


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Bypass Option #3: Reinforced Block Open Channel This option proposes to construct a reinforced block open channel. Design parameters and construction techniques are per a Tela municipal construction quote of 707 Lempira per linear meter. Recommended Construction Procedures:



3. Construct/Install the proposed reinforced concrete block channel with interior dimensions no less than 0.5 m x 0.5 m. Ideally, the flow will occupy only half of the constructed channel height at maximum flow. The remaining 0.25 m of freeboard depth is for occurrences of heavier than expected flow rates.

4. Insert a 0.46 m (18”) diameter PVC pipe or equivalent into the existing concrete headworks as shown on page 4/4 of drawings in Appendix A-4. Run the length of pipe through the existing concrete wall to connect existing influent channel with bypass channel.

5. Allow the ability to shut off wastewater flow through the 0.46m (18”) pipe with use of a ball operated shut-off valve, cap and flange fitting, or other functional flow stopping device. This fitting will control flow of the wastewater between the headworks and the concrete diversion channel.

6. Construct the concrete channel in ordinance with local building techniques and operations.


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Reinforced Block Open Channel Cost:

Table 3: Reinforced Block Open Channel



Total

Construction of Bypass Channel

Material + Labora m 707 120 84,840 84,840 Total (Lps.) L. 84,840 Total ($US)b US $4,490

a. Prices based on construction quote from Municipality of Tela, March 2006

b. Exchange rate of 18.895 Lps/$US, April 23, 2006

Sources: Forex Capital Markets, 2003; Municipality of Tela, 2006; Cost Comparison Option #1 – Concrete Square Open Channel Option #2 – Circular Plastic Pipe Option #3 – Reinforced Block Open Channel

Concrete Channel cost (Lps.) = Lps. 88,369 Concrete Channel cost (US) = US $4,677

Pipeline cost (Lps.) = Lps. 172,801 Pipeline cost (US) = US $9,145

Reinforced Block Channel cost (Lps.) = Lps. 84,840 Reinforced Block Channel cost (US) = US $4,490


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Our recommendation is that Option #3 be selected since it uses local knowledge and methods and is most cost effective.

REMOVAL OF SOLIDS IN PRIMARY LAGOON Sludge Removal Requirement There are approximately 3,000 m3 of sludge in the primary lagoon. Once the sludge has been removed from the lagoon, it is preferable to dispose the sludge on-site. On-site disposal minimizes the cost of transport, the risk of environmental contamination and human contact. Please see the lower left corner of Figure 3 for a plan view of the lagoon and the proposed sludge storage site. Figure 4 below shows the relative location and positioning of the proposed disposal area, which is circled and indicated with an arrow.

Figure 4: Proposed sludge storage area is visible in the background.

Drainage and Drying of Primary Lagoon When planning the removal of sludge from a primary lagoon, it is ideal to have the sludge as dry as possible so it can be removed by dry or semi-dry methods. Dry removal methods cost less than wet removal methods, which use pumps and/or dredges. It is imperative to drain the lagoon and allow the sludge to dry during the driest continuous


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months of the year. When the depth of sludge in a primary lagoon is less than 0.3 m, drying is relatively fast and sludge removal is easy with front end loaders. Unfortunately, the sludge depth at Tela's primary lagoon is over 2 m deep and semi-dry removal will be necessary using an excavator. Cost of Drainage: The primary lagoon should be drained using a siphon hose, and therefore the only cost is the procurement of an appropriate hose. If, during the course of sludge drying, a sufficient amount of water should drain out of the sludge it might be necessary to pump this settled water into the secondary lagoon to improve drying results. As a contingency, the cost of this pump has been estimated and presented here in Table 4:

Table 4: Cost of Primary Lagoon Drainage



Totala

Drainage of Primary Lagoon

4” Water Pump and hose (if necessary)b

day 390 10 3,900 4,913

Total (Lps.) L. 4,913 Total ($US)c US $260

a. Inflation used if value was taken from March 2003 Boletín Estadístico. Inflation rate based on average



b. Prices used from the Boletín Estadístico, Marzo 2003


Sources: Boletín Estadístico, March 2003; CIA, 2006; Forex Capital Markets, April 2003


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Sludge Removal and Disposal The following section estimates the total quantity, time and price to remove sludge from the primary lagoon in a semi dry state using an excavator. The municipality should make all preparations to schedule the use of an excavator as described below, plan accordingly for the work to be done, and make the necessary inquiries into available land close to the wastewater treatment system that would serve as an appropriate disposal site. Recommended Construction Procedures:

1. Excavate the disposal volume in the 812 m2 available area adjacent to the inlet to the primary pond as seen in Figure 3. (Page 3/4 of the plans, Appendix A-3 and Figure 4). • 3:1 slope on the sides • ≈ 3 m depth • Area of top ≈ 812 m2 • Area of middle ≈ 356 m2 • Area of bottom ≈ 76 m2

2. Place ≈ 0.15 m of gravel in an even layer covering the bottom of the

excavated pit to serve as a draining mechanism. The bottom should be sloped so any leachate will drain back into the primary lagoon.

4. Fill pit with sludge until full then cover with excavated soil (minimum 0.3m

cover). 5. Remaining sludge, (3,000 m3 - 1,145 m3) = 1,855 m3, should be disposed of in

a combination of one or more of the following ways: • Onsite. The disposal excavation may be refilled as the buried sludge


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settles. • Onsite. A thin layer of sludge may be spread around the perimeter of the

system. • Onsite. Sludge may be moved to areas of the primary lagoon that have

low sludge buildup during normal operation, or spread evenly on the floor of the lagoon.

• Offsite. On local, acquirable lands. • Offsite. At the discretion of the municipality.

Equipment:

• Caterpillar 350 L (286 hp) or equivalent with a 1.5 m3 bucket capacity • Use the longest boom available. Also, a bucket with no teeth is required to

excavate sludge without damaging the lagoon bottom.

Figure 5: Typical excavator. Note the boom length is critical.

Sludge Removal Work Time Required Calculations:

Assume:

• 45 second cycle time • 2/3 bucket capacity for handling of wet sludge


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• 50 minute hour

Excavation of Sludge Storage Area:

Time Required

Facultative Pond Sludge Removal:

Time Required

Total Time = 56.4 hrs

Cost of Sludge Removal

• ~1,200 m3 of wet sludge will be placed in the disposal volume • ~1,800 m3 will be disposed onsite or nearby • Excavation price based on Tracked Excavator, (Estadistico, March 2003) • Costs per day are based on an 8-hour work day


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Sludge Removal Cost Estimate: The following table presents the estimated cost of sludge removal with an excavator and crew. The cost is based on an estimated excavator cycle time, and bucket load volume.

Table 5: Sludge Removal Cost Estimate



Totala

Disposal Volume Excavation

Equipment Operationb hour 1,114 12 13,368 16,840 1 Excavator Operatorb day 250 2 500 630 1 Laborerb day 100 3 300 378

Sludge Removal Equipment Operationb hour 1,114 45 50,130 63,149 1 Excavator Operatorb day 250 6 1,500 1,890 1 Laborerb day 100 6 600 756

Sludge Drying/Draining River Rock / Gravelb m3 210 20 4,200 5,291 4” Water Pumpb day 390 10 3,900 4,913

Total (Lps.) L. 93,846 Total ($US)c US $4,967 Total (Lps.), x2 Factor of Safety L. 187,692 Total ($US)c x2 Factor of Safety US $9,933 a. Inflation used if value was taken from March 2003 Boletín Estadístico. Inflation rate based on average





Sources: Boletín Estadístico, March 2003; CIA, 2006; Forex Capital Markets, April 2003


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Total Sludge Removal Cost:

Total Sludge Removal cost (Lps.) = Lps. 187,692 Total Sludge Removal cost (US) = US $9,933

Excess Sludge Storage Options

Figure 6: Potential onsite sludge storage locations.


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FLOW MEASUREMENT Parshall Flumes Parshall flumes are an accurate, low cost, and simple technology for measuring flow rates. Proper geometry and calibration, however, are crucial for accurate flow measurement. A Parshall flume must have a specific throat width, dimensions, and hydraulic gradient for the expected flow range. For Tela’s wastewater treatment system, the best option for flow measurement is to purchase a prefabricated Parshall flume to ensure that all the dimensions are correct and to avoid the problems encountered with the previous two flumes. Care must be taken to install the flume correctly as well. Analysis of Existing Parshall Flume Presently there are two Parshall flumes on-site. The first flume was constructed around 1994, and due to incorrect design and construction, it could never be used to measure flow accurately, as shown in Figure 7. The second flume, constructed in 2004, is too large for existing flows and is ineffective for flow measurement. The second flume’s 0.67 m throat width is almost 4.5 times the 0.15 m throat width required for the flow ranges encountered at Tela’s treatment system. The second Parshall flume is shown in Figure 8.


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Figure 7: The original Parshall flume built in

1994.

Figure 8: The most recent Parshall flume,

built in 2004.

Sizing and Installation of Prefabricated Parshall Flume Sizing: Basic flow measurements were taken in January 2006. The flow ranges for Tela measured between a minimum of 0 m3/s (When pumps are not running) up to a maximum of 7,500 m3/day. A 0.152 m (6”) throat width prefabricated Parshall flume is appropriate for this flow range as summarized below in Table 6, (Oakley, 2005).

Table 6: Parshall Flume Flow Ranges

Qmin Qmax Throat Width, m m3/s m3/day m3/s m3/day

0.076 0.0008 69 0.0538 4,648 0.152 0.0015 130 0.1104 9,539 0.229 0.0025 216 0.2519 21,764


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Installation: Since the new 0.152 m throat width Parshall flume is so much smaller than the existing flume, there is adequate clearance to mount the new flume into the existing flume channel. Installation of the Parshall flume should be completed during the period when system influent is being diverted to the secondary pond and before the reactivation of the primary lagoon. Parshall Flume Cost:

Table 7: Parshall Flume Cost Estimate



Totala

Prefabricated Parshall Flume

Purchaseb ea 22,674 1 22,674 22,674 Shippingb ea 15,116 1 15,116 15,116

Installation Material- Concretec m3 1,325 0.6 795 1,001

Labor, 3 Peoplec day 800 2 1,600 2,016 Total (Lps.) L. 40,807 Total ($US)d US $2,160 a. Inflation used if value was taken from March 2003 Boletín Estadístico. Inflation rate based on average



b. The flume cost, US $1,200 is based on a price quote from Clipper Controls Inc. in San Francisco. It is

assumed that US $800 incidental packaging and shipping cost from San Francisco, USA to Tela,

Honduras will be required. This price quote, shown above in Table 7, can be referenced in Appendix A.

c. Prices used from the Boletín Estadístico, Marzo 2003

d. Exchange rate of 18.895 Lps/$US, April 23, 2006

Sources: Boletín Estadístico, March 2003; Clipper Controls, Inc., 2006; CIA, 2006; Forex Capital Markets, April 2003


24

EFFLUENT REUSE The objective of the effluent reuse component of this project is to improve the overall sustainability of the system by using the effluent as a revenue-making resource. The effluent reuse project will deliver treated wastewater from the tertiary lagoon to a municipally owned ornamental plant nursery. SEEHD and the Municipality are working to relocate the existing nursery to a vacant site adjacent to the wastewater treatment system, across the Río Hylan (Figure 10). The nursery, which was originally donated by CARE International, is used to culture ornamental plants for use by the Municipality and Tela residents.

Figure 9: The existing nursery and setup that will be relocated.

Proposed Plan for the Pilot Nursery Existing Nursery Site: The municipality of Tela currently operates a nursery in a section of town approximately 5 kilometers west of the wastewater lagoon system. The nursery produces ornamental plants and trees for use in the community. As shown in Figure 9, plants are potted and watered individually. The nursery currently has serious problems with availability of irrigation water during the dry season. As a result, nursery personnel are very interested in relocating the nursery adjacent to the lagoon system where they could utilize the effluent as an essentially limitless supply of irrigation water.


25

Figure 10:The proposed nursery site.

Proposed Nursery Site: The site shown in Figure 10, is located south of the Treatment system and can be seen to the left when crossing the Rio Hylan Bridge going towards the treatment system. The proposed relocation area near the wastewater treatment system is currently being unused and the parcel owner is unknown. SEEHD will continue to investigate the status of this land in hopes of realizing its potential as a community resource.

Pilot Nursery Proposal:

It is proposed that treated effluent from the treatment system be transported across Rio Hylan and delivered for on-demand use at the new nursery site. Water can be siphoned from the tertiary lagoon south across the Rio Hylan bridge (Figure 13) to the proposed nursery site. The existing bridge bottom could support the pipe or hose transporting the irrigation water to the nursery site. A fixture would be placed at the nursery outlet to supply on-demand water. A relatively constant grade must be maintained between the pipe’s inlet and outlet to ensure consistent gravity flow. The siphon must be located at the exit of the tertiary lagoon to assure the siphoned water has received complete treatment. The reuse component may be implemented at anytime, and as soon as funds secured for the relocation of the nursery and purchase of the adjacent property (Figure 10).


26

Effluent Water Quality

A water quality study was completed on Tela’s wastewater treatment system effluent by SEEHD in 2006 and ECOMAC in 2004. These studies examined the health risks associated with effluent reuse and the chemical quality of the water for agricultural applications. Evaluation of the microbiological quality of the treated wastewater was based on results and values from the study performed by ECOMAC in 2004. The chemical quality testing was performed by SEEHD and an independent laboratory, Jordan Labs, in San Pedro Sula, Honduras.

Figure 11: The final treated effluent leaving the treatment system.

Microbiological Quality: The following results are taken from the monitoring study performed by ECOMAC (2004) on the performance of Tela's lagoon system. They specifically identify the removal of fecal coliforms and helminth eggs during the dry and wet seasons.


27

Table 8: Removal of Fecal Coliforms and Helminth Eggs in Tela Lagoon System.

Parameter

Units

Influent

Effluent Lagoon

1

Effluent Lagoon

2

Effluent Lagoon

3 Fecal Coliforms1 MPN/100mL

Dry Season: 6.49E+06 7.43E+06 2.69E+04 3.44E+04 Wet Season: 2.97E+06 8.44E+05 1.13E+05 7.94E+03

Helminth Eggs2 Eggs/L

Dry Season: 2 (0—4)

0 0 0

Wet Season: 9 (4—16)

0 0 0

1. Numbers are geometric means of daily samples taken on three consecutive days. 2. Numbers are arithmetic means of daily samples taken on three consecutive days. Numbers in parentheses are the ranges of values. World Health Organization Guidelines: Table 9 shows the World Health Organization guidelines (WHO, 1989) for irrigation with wastewater effluent. The Tela lagoon effluent easily satisfies the WHO guideline for Category B, Restricted Irrigation, which includes irrigation of cereal crops, industrial crops, fodder crops, pasture, trees, and any vegetable or fruit crops not eaten raw.

Sustainable Wastewater Treatment and Reuse – 2006

28

Table 9: World Health Organization Recommendations,

And Microbiological Guidelines for Wastewater Use in Agriculturea.

Category

Reuse Conditions

Exposed Group

Intestinal Helminthsb

(Arithmetic Mean Number of Eggs

per Literc)

Fecal Coliforms

(Geometric Mean Number per

100 mLc)

Wastewater Treatment

Expected to Achieve the Required

Microbiological Guideline

A

Irrigation of crops likely to be eaten uncooked, sports fields, public parksd

Workers Consumers

Public

≤ 1

≤ 1,000

A series of stabilization ponds designed to achieve the microbiological quality indicated, or equivalent treatment

B

Irrigation of cereal crops, industrial crops, fodder crops, pasture, and treese

Workers

≤ 1

No standard recommended

Retention in stabilization ponds for 8—10 days or equivalent helminth and fecal coliform removal

C

Localized irrigation of crops in Category B if exposure to workers and the public does not occur

None

Not applicable

Not applicable

Pretreatment as required by irrigation technology but not less than primary sedimentation

a. In specific cases, local epidemiological, sociocultural and environmental factors should be taken into account and the guidelines modified accordingly. b. Ascaris and Trichuris, species and hookworms. c. During the irrigation period. d. A more stringent guideline limit (≤ 200 fecal coliforms/100mL) is appropriate for public lawns, such as

hotel lawns, with which the public may come into direct contact. e. In the case of fruit trees, irrigation should cease two weeks before fruit is picked, and no fruits should be

picked off the ground. Sprinkler irrigation should not be used. Source: WHO, 1989.


29

Physical-Chemical Quality: The following table summarizes the results of the physical-chemical water quality tests performed in January 2006 on the tertiary pond effluent:

Table 10: Physical-Chemical Water Quality Results for Tertiary Pond Effluent.

Parameter Units Results Calcium (Ca) mg/L as CaCO3 21.4 Sodium (Na) mg/L 21 Magnesium (Mg) mg/L as CaCO3 8.0 Total Nitrogen (N)* mg/L < 20 pH pH units 8.0 Total Alkalinity mg/L as CaCO3 103 Total Dissolved Solids mg/L 177 Electrical Conductivity mS/m 27 Sodium Adsorption Ratio (SAR) -- 1.7

* Assumed Value Evaluation of Water Quality Guidelines for Irrigation The effluent from Tela’s treatment system meets the Food and Agriculture Organization’s (FAO) guidelines for no restriction on water use for irrigation of crops. A summary of the FAO's guidelines on irrigation water quality are as follows (Mara, 2003):

1. Total dissolved solids (TDS) should be less that 450 mg/L for unrestricted irrigation of crops.

2. Electrical conductivity (ECw) should be less than 75 mS/m at 25°C for unrestricted irrigation.


30

3. The sodium absorption ratio (SAR) should be less than 18 for unrestricted irrigation. The sodium absorption ratio is dimensionless and defined as:

Where the respective ions are expressed as milliequivalents per liter.

4. Most crops can tolerate up to 2 mg/L of Boron in irrigation water. This parameter was not evaluated due to the high cost of testing; it is assumed to not be a factor in ornamental plant application.

5. Most crops can tolerate 30 mg/L of total-N. Due to the high quality of the final effluent, it is assumed that the total nitrogen is less than 20 mg/l.

6. For irrigation waters, the pH should be within 6.5 – 8.4. Design of Effluent Delivery to Nursery Site As mentioned previously, it is proposed that the nursery be moved to the location near the treatment system and that the treated wastewater be used for year-round irrigation. The site is adjacent to the lagoon system, approximately 0.5 hectares in area, and is currently vacant as seen in Figure 10. The most cost effective method to transport the treated wastewater to the proposed site is to use a gravity fed pipe that exits the tertiary lagoon to the new location. A spigot/valve, placed at the discharge end of the pipe, would supply on-demand water for filling watering cans for hand irrigation. As a precaution, the nursery should be fenced to provide security for the nursery and to eliminate the opportunity for contact between the public and the treated wastewater.


31

Design Criteria: Horizontal distance = 60 m Vertical drop of pipe end to end = 0.7 m Length of bridge to support pipe = 45 m Pipe will be PVC or plastic equivalent

Figure 12: The proposed irrigation supply delivery plan.

(1) Pipe inlet to tertiary lagoon (2) Top of bank of tertiary lagoon (3) Pipe outlet to proposed nursery site. Ball Valve Spigot

Figure 13 shows the bridge mentioned above looking across the Rio Hylan towards the treatment system.


32

Figure 13: The Rio Hylan Bridge, facing north towards the treatment system.

Calculations:

Using Bernoulli’s Theorem

Where: p = pressure, N/m2

ρ = density of water, kg/m3 V = water velocity, m/s g = acceleration of gravity, 9.81 m/s2 γ = water specific weight, kN/m3

z = head of water, 0.7 m hL = expected head loss, m To solve for the pipe diameter, exit velocity, and head loss due to friction, iterative calculations must be made using the following equations:


33

1) Colebrook Equation, determined the friction factor, f as a function of pipe material, Reynolds number, and pipe diameter

Where; f = pipe friction factor ε = pipe equivalent roughness, assumed to be 1.5x10-6 m D = pipe diameter Re = Reynolds Number

2) Reynolds Number Equation

for pipe flow

Where; µ = dynamic viscosity, N·s/m2

V = flow velocity, m/s D = pipe diameter, m ρ = density of water, kg/m3

3) Exit Velocity, in terms of Bernoulli’s Theorem


34

Where; p1 = p3 = V1 = z1 = 0 and the head loss, hL is found by

*Source: (Viessman, 2005) Where; f = pipe friction factor l = pipe length, m D = pipe diameter, m KL = friction factor for fixtures and bends in pipe So;

, z3 = 0.7m

Using Microsoft Excel to solve the previous equations iteratively for f (the pipe friction factor), the following set of data was produced. A KL value of 0.1 was assumed for minor fixture losses associated with head loss through pipe bends and flow regulating valves. The analysis shown in Appendix A suggests that a 1½″ to 2″ pipe will be the best option for an irrigation delivery system. For supporting head loss calculations with graphs please see Appendix A-5.


35

Table 11: Siphon Flow Characteristics vs. Pipe Diameter

Pipe Diameter, in

Pipe Diameter, m

Maximum Flow, L/s

Associated Head Loss, m

Reynolds Number

1” 0.0254 0.224 0.689 12,441 1½” 0.0381 0.668 0.681 24,741 2” 0.0508 1.441 0.672 40,017 3” 0.0762 4.210 0.652 77,954 4” 0.1016 8.927 0.632 123,989

The following materials will be required for the water delivery portion of the irrigation project:

• Approximately 60 m of 1½″ to 2″ PVC schedule 40 pipe or hose • Ball valve hose spigot (fixture size to be determined) • Hand pump to maintain, or recreate siphon. (Optional) • Various pipe fittings (to be determined)

Cost of Effluent Delivery System: The following table summarizes the estimated cost of constructing the effluent delivery system from the exit of the tertiary system, across the Rio Hylan Bridge, to the proposed nursery site.


36

Table 12: Estimated Cost of the Effluent Delivery System.



Totala

Material 2” PVC Pipeb m 130 60 7,800 9,826 Accessoriesb 8,000 10,078

Installation PVC Installb m 8 60 480 605 Accessoriesb 500 630

Total (Lps.) L. 21,138 Total ($US)c US $1,119 a. Inflation used if value was taken from March 2003 Boletín Estadístico. Inflation rate based on average





EFFLUENT REUSE FOR AQUACULTURE Aquaculture for tilapia production is a burgeoning industry in Honduras and it is feasible to produce tilapia in the tertiary lagoon, which then could be sold in local markets and thus would be an additional revenue source for the municipality. Evaluation of World Health Organization Guidelines for Aquaculture Table 13 shows WHO's guidelines for wastewater reuse in aquaculture. The effluent from the secondary lagoon, as shown in Table 8, met these criteria in the dry season and was just slightly over it in the wet season. After the primary pond is desludged, it is assumed that the <105 fecal coliforms/100mL criteria will be able to be satisfied 100% of the time.


37

Table 13: Microbiological Criteria for the Aquacultural Use of Wastewater.

Average of Series of Samples Taken During Period of Reuse

Reuse Process

Viable Trematode Eggs (Schistosoma species in Honduras)

Eggs/L (Arithmetic Mean)

Fecal Coliforms

MPN/100mL (Geometric Mean)

Fish Culture

0

<105

Macrophyte Culture

0

<105

Source: Mara, 2003. Estimated Tilapia Production in Tertiary Lagoon The surface area of the existing tertiary pond will dictate the allowable flow that can be diverted into it, though ultimately the BOD and total-N will determine the allowable loadings and hence flow. The area of the tertiary pond is

The quantity of fish that can be produced using a 0.62 ha fish pond can be determined using the assumptions listed by Mara (2003), which include a 70% fish survival rate, a harvested fish with a sellable weight of 250g per fish and a total of 2 harvest a year:


38

Estimated Cost and Benefit of Annual Tilapia Production To produce this quantity of fish, an initial investment in fingerlings must be made. Based on an allowable fish density of 2 fish/m2 the total number of fingerlings purchased per year would be:

At an estimated price of $0.10 per pre-sexed fingerling (male) the initial investment for Tilapia production would be:

This production could produce an annual revenue (given consistent market prices) of:

Total Annual Income From Tilapia Farming = $6,200

And after a period of 10 years, this would equal

10-Year Income

This amount could be easily enough to pay for desludging operations, maintenance, and a full time operator/maintenance person. Depending on the current rate of electricity prices, this revenue may also be used to offset the cost associated with the pump station electricity use.


39

COMMUNITY SURVEY Community Survey Background In January 2006, Chico State’s SEEHD group completed a community survey of residents in the neighborhood directly surrounding Tela’s wastewater treatment facility. A copy of the survey is in Appendix A (page A-12). The survey was part of the chapter’s project assessment and the purpose of the survey was to evaluate the community’s:

• Awareness and knowledge of the treatment system, • Opinion of the system and confidence in the treatment it provides, • Perceived or real impacts of the system, • Most common household illnesses and what factors they are attributed to, • Opinion of wastewater reuse, • Current sources of water for drinking and household tasks, • Type of sanitary service present in the home, • Methods for disposing household solid waste, and • Any fees associated with connection to the wastewater treatment facility.

The survey was written by Erin Smith, and was conducted by Erin Smith, Sadie McEvoy and Isabel Rivera. Erin Smith is a cultural anthropologist from CSU Chico with a specialty in Latin American cultures. Sadie McEvoy is a civil engineering student and member of the CSU Chico group SEEHD. Isabel Rivera is the director of Unidad de Pacto por La Infancia y Juventud, Municipality of Tela. Isabel, Erin and Sadie walked through the neighborhood adjacent to Tela’s wastewater treatment facility, surveying adult individuals at random. Isabel conducted the interviews with community members and Sadie recorded and relayed the responses to Erin. The survey included ten community members and lasted four hours (9AM-1PM). Three men and seven women were interviewed. The men reported their vocations as construction foreman, auto mechanic and retired, and their ages as 51, 49 and 60 years old, respectively. Five women reported their vocation as homemaker. The remaining two women reported their vocation


40

as homemaker and corner store owner. The women’s ages were reported as 70, 39, 56, 45, 26, 58 and 31 years old. All interviews were conducted with individuals and only one representative was interviewed from each home and business. Survey Feedback and Local Impact Knowledge and Opinion of Wastewater Treatment System: Nine interviewees were familiar with the treatment system and understood that it collects wastewater. A young mother, who lived two blocks from the site, was not aware of the system and did not express any interest in it. Those who were familiar with the system had varying degrees of knowledge about the system’s treatment capacity. The men interviewed demonstrated impressive understanding of the system. Both the mechanic and the foreman explained that natural processes treat wastewater before it is discharged to the river. These men expressed confidence in the treatment system and its efficacy. Three of the women interviewed were not aware that the system was a treatment facility and believed it simply collected wastewater to discharge to the river. The remaining four women understood that the system treats the wastewater and expressed varying degrees of faith in its efficacy. Categorically, the women were less knowledgeable about the system, and reported less confidence in its treatment capacity, than the men interviewed. These results suggest that confidence in the treatment system is directly proportional to the level of knowledge of the system. One source of confusion about the system’s treatment ability is that there is no machinery or chemicals to show that the water is being treated. Understandably, it is hard for the community to believe that an invisible, natural process is cleaning the wastewater. A second source of confusion is that the bay and the river adjacent to the treatment system are both contaminated. Half of the interviewees contributed this contamination to the waters discharged from the treatment facility. Although this misconception is understandable, the treatment system is not responsible for the contamination.


41

Opinion of Wastewater Reuse Projects: The seven women and the retired male interviewee expressed reservations to the idea of wastewater reuse for agriculture or aquaculture applications. When questioned about their resistance to wastewater reuse, the primary concern of interviewees was the safety of the treated water. When asked if they would support reuse if there were an assurance that the water was clean and safe, the retired male and five female interviewees said they would be supportive of reuse in agriculture and aquaculture. Two women interviewees stated that they were opposed to the concept of reuse and would not support it, even with improved water safety assurance. Two male interviewees, the mechanic and the foreman, reported that they were comfortable with the current water quality and would support reuse in agriculture and aquaculture. All interviewees were supportive of reuse in horticulture applications, with the current water quality. Five female and all of the male interviewees were familiar with the idea of wastewater reuse, to varying extents. The mechanic and the retired male interviewee each knew of specific reuse projects in Latin America and the United States. Other interviewees said they had heard of reuse from either TV or other sources. The male interviewees reported greater support for reuse than the women interviewees did. Reported Impacts of the System: Questions regarding the impacts of the system received the greatest variety in responses. Three men and five women expressed concerns about environmental impacts of the system. The primary concern of this group was contamination of the river and bay by the treatment system’s discharge. The three interviewees who expressed full confidence in the treatment system stated that they did not believe the system’s discharge was contaminating the river or bay. However, two male and one female interviewee expressed concern about wastewater that leaks onto the roads, before it arrives at the system. The interviewers confirmed the existence of the leaks. Two female interviewees expressed no concern for environmental impacts. All interviewees complained of bad odors from the system, during rains and wind. The interviewers could not confirm whether the treatment


42

system is in fact the source of the odors. Many interviewees living directly beside the treatment system expressed concern for health impacts. One interviewee claimed to have malaria, which he attributed to mosquitoes from raw wastewater standing in the streets. Two female interviewees complained that children contracted parasites and frequently had diarrhea, which doctors told one woman came from contact with the soil and contaminated water. Interviewees reported no social impacts or stigma from living beside the system. Reported Household Illnesses: The most common household illness reported was a cough, which all interviewees attributed to climate. Four interviewees felt their ailment could also be attributed to the dust from unpaved roads and possibly contaminated living environment. Every interviewee named cough as the primary household illness, followed by flu/cold. Two of the seven households with small children reported diarrhea as a common illness in the children. Both mothers attributed the diarrhea to contact with unsanitary animals, soil and water. Domestic Practices Reported by Community: The sanitary services reported are approximately 50% septic tank and 50% sewer connection. Interviewers witnessed wastewater discharging from the residential area into the river adjacent to the treatment system, suggesting that not all households are served by a septic tank or sewer connection. All interviewees stated that their garbage is collected by the city, on a weekly basis. All interviewees stated that they paid a fee for water service and sewer hookup. All interviewees claimed to use purchased bottled water for drinking and tap water for cooking and housework.


43

CONCLUSIONS AND RECOMMENDATIONS In January 2006, SEEHD completed a project assessment trip to the existing wastewater treatment system that serves approximately 8,000 persons in the area of Tela Vieja, in Tela, Honduras. The problem of greatest importance is the sludge buildup in the primary lagoon. To avoid system failure, this problem must be addressed and the sludge removed as soon as possible. Second, it is important that a new, correctly calibrated Parshall flume be installed to enable accurate flow measurement, predict loading rates, and plan for future sludge removal. Finally, an effluent reuse project is proposed that will utilize a valuable resource and improve the system’s sustainability, as well as demonstrate the practicality of effluent reuse. The specific conclusions and recommendations of this report are summarized as follows:

1. Construct an open reinforced concrete block diversion channel around the primary

lagoon for the system influent, ending at the entrance to the secondary lagoon. Divert influent to secondary lagoon.

2. Drain the primary lagoon and remove the sludge in a semi-wet state using available excavator and equipment. Dispose of sludge through a combination of on-site burial and/or local land application (not for crop or pasture fertilization).

3. Install a prefabricated Parshall flume inside the existing flume. 4. Siphon a small portion of effluent from the tertiary lagoon, across Rio Hylan, to a

pilot nursery owned and operated by the Municipality. The water will flow by gravity.

For a work timeline please see page A-10.


44

Diversion Channel It is the conclusion of this report that the best approach for diverting the system influent to the secondary lagoon is to construct a concrete open channel around the first lagoon. The diversion channel is to be constructed from the base of the concrete headworks, as seen in the AutoCAD drawings attached in Appendix A (pages A-1 through A-4), to the inlet of the secondary lagoon. Primary Lagoon Drainage It is the conclusion of this report that the most effective procedure for draining the primary lagoon is as follows;

1. Stop flow into the primary lagoon by diverting the influent into the secondary lagoon via the proposed diversion channel.

2. Drain the as much water as possible from the primary lagoon into the second lagoon via siphon.

3. Install a pump near exit of primary lagoon and run as necessary to pump out water that settles out from sludge.

4. Let the sludge near the entrance of the primary lagoon dry for as long as possible during the dry season. (Roughly 2 months)

Sludge Removal The removal of sludge is the most important part of this project. It is important to consider the health risks inherent in the disposal of wastewater sludge. Due to the latency and high persistence of helminth eggs, it is critical to avoid human exposure to the removed sludge for as long as possible. Therefore, all methods of sludge disposal should consider and minimize potential for human and animal contact.


45

The field assessment found that there is enough area in the south east corner of the lagoon for an excavation to deposit approximately half of the sludge from the primary lagoon. The remainder will have to be transported offsite, perhaps to several adjacent areas in the proximity of the system. Flow Measurement Flow measurement allows for an accurate prediction of system loading and helps operators estimate maintenance intervals and plan accordingly. It is the recommendation of this report that the existing flume is ineffective for flow measurement and something must be done. Based on the flow ranges found at the Tela Wastewater Treatment System, it is the conclusion of SEEHD that a pre-fabricated fiberglass Parshall flume with a 6” throat width be installed. It is recommended that this work is done while the system influent is being diverted around the primary lagoon and before the primary lagoon becomes active again. It is utmost importance that the flume be installed correctly. SEEHD is committed to using all available resources to ensure that installation is done properly. Effluent Reuse Because the tertiary pond's effluent satisfies WHO's guidelines for Category B restricted irrigation, it is recommended that the municipal nursery be moved to the proposed area adjacent to the lagoon system and that a pipeline be constructed to deliver the tertiary pond's effluent to the nursery. This will allow year round irrigation at the nursery and will foster sustainability of the lagoon operation by using the final effluent as a resource. It is our recommendation that the Municipality begin planning now for the implementation of this project in the spring and summer of 2007. SEEHD is committed to the success of this project and will do everything within reach to assist Tela in securing funding from various aid organizations.


46

REFERENCES

Boletín Estadístico, Cámara Hondureña de la Industria de la Construcción, Tegucigalpa/San Pedro Sula, Honduras, Marzo 2003. CIA- The World Factbook, Honduras Economic Statistics, April 2004. http://www.cia.gov/cia/publications/factbook/geos/ho.html. ECOMAC, Informe de Monitoreo Laguna de Estabilización Tela: Proyecto Monitorio de Sistemas de Estabilización de Tratamiento de Aguas Negras. U.S. Army Corps of Engineers, Mobile District, Tegucigalpa, Honduras, C.A.: ECOMAC, March 2004. Flume Price Quote, Clipper Controls, Inc., 330 Townsend St. Ste. 107, San Francisco, CA 94107-1630. Phone: (415)-808-1469 FOREX Capital Markets, Honduras Currency Exchange Rates, April 23, 2004. http://www.fxcm.com/. Mara, D., Domestic Wastewater Treatment in Developing Countries. London: Earthscan, 2003, pp. 42-43, 230-261. Oakley, S., Lagunas de Estabilización en Honduras: Manual de Diseño, Construcción, Operación y Mantenimiento, Monitorio y Sostenibilidad. USAID, June 2005. pp 66-69, 175-204. Viessman, W. Jr., Hammer, M. J., Water Supply and Pollution Control. London: Pearson Education Ltd., 2005, pp 126-144. WHO, Health Guidelines for the Use of Wastewater in Agriculture and Aquaculture, Report of a WHO Scientific Group, Technical Report Series, No. 778, World Health Organization, Geneva, 1989.

APPENDIX A


A-1 Drawings Not To Scale (11x17 Original)

AutoCAD Drawings

SEEHD (Sustainable Engineering and Environmental Health for Development)


A-5

Tables and Graphs: Work Plan for Effluent Delivery The following tables and graphs relate to the calculations done in the Work Plan for Effluent Delivery section of this report. Table 14 and Graph 1 illustrate the potential pipe sizes that could be used and their associated head loss. As can be seen as pipe diameter increases, head loss decreases

Table 14: Pipe Diameter with Associated Flow and Head Loss

Pipe Diameter, in

Pipe Diameter, m

Maximum Flow, L/s

Associated Head Loss, m

Reynolds Number

1” 0.0254 0.224 0.689 12,441 1½” 0.0381 0.668 0.681 24,741 2” 0.0508 1.441 0.672 40,017 3” 0.0762 4.210 0.652 77,954 4” 0.1016 8.927 0.632 123,989

Graph 1: Head Loss vs. Pipe Diameter


A-6

Table 15 and Graph 2 show the relationship between potential pipe sizes and the dead load experienced by the Rio Hylan Bridge due to the weight of the pipe plus the weight of the water inside the pipe.

Table 15: Pipe Diameter and Related Dead Load on Rio Hylan Bridge

Pipe Diameter, m Volume of Pipe Across Bridge, m3 Assume 45 m Length

Static Weight of Pipe (due to water) to be Supported by Bridge, kg

0.0254 0.023 22.9 0.0381 0.051 50.8 0.0508 0.091 90.7 0.0762 0.205 204.4 0.1016 0.365 363.9

Graph 2: Static Pipe Weight (Dead Load) vs. Pipe Diameter


A-7

Graph 3 shown below shows the increase in flow rate as the diameter of the effluent reuse delivery piping increases.

Graph 3: Max Flow Rate vs. Pipe Diameter


A-8

Table 16: Effluent Reuse Spreadsheet

Value Variable Units 7.603197293 Pipe Diameter 0.0762 D M

Pipe Length 60.0 l m Colebrook Formula:

Friction Factor 0.0173 f Reynolds Number 81530.1284 Re 0.361422251 Density 996.9500 ρ kg/m3 Velocity 0.9659 V m/s

Dynamic Viscosity 0.0009 µ N*s/m2 Equivalent Roughness 0.0000015 ε m Minor Fixture Loss 0.1 KL Head Loss 0.6477 hL m Head Difference 0.7 h m Flow 4.403 L/s


A-9

Table 17: Effluent Reuse Sample Calculations

Results Pipe

Diameter (inches)

Pipe Diameter (meters)

Flow Re # Volume for 45m

Pipe Weight

(kg)

Pipe Weight

(lb)

head loss, m

1" 0.0254 m 0.224 L/s 12441 0.023 22.9 50 0.689 1.5" 0.0381 m 0.668 L/s 24741 0.051 50.8 112 0.681 2" 0.0508 m 1.441 L/s 40017 0.091 90.7 200 0.672 3" 0.0762 m 4.210 L/s 77954 0.205 204.4 450 0.652 4" 0.1016 m 8.927 L/s 123989 0.365 363.9 801 0.632

The following table outlines the iterative steps taken to solve for the friction factor, f, of the proposed pipe crossing Rio Hylan.

Table 18: Iterative Procedure to Produce Friction Factor, f


A-10

Timelines and Work Plans

Table 19: 2006 Timeline and Work plan Schedule.

Task: January February March April May June July August September October November December

Tela Report

Presentation

Report

Presentation,

Tegucigalpa

Secure

Funding

Notify Work

Crews

Reserve

Excavator

Purchase

Bypass

Materials

Deliver

Materials to

Site


A-11

Diversion

Channel

Table 20: 2007 Timeline and Work plan Schedule.

Task: January February March April May June July August September October November December

Diversion

Channel Construction

Lagoon

Drainage Siphon

Sludge

Drying

Dry sludge during

dry season

Sludge

Removal Excavate

Flume

Installation Install

Reuse

Pipeline

Construction Construction

Nursery

Construction Construction


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Community Survey and Interview Questions

Encuesta para la Comunidad por parte de Ingenieros Sin Fronteras: Tela, Honduras 11 Enero, 2006 Nombre: ________________ Edad: ____ Sexo: M__ F__ ¿Cuantas personas viven en su casa? ____ Ocupación: ______________________________ Objetivo: Realizar un diagnostico comunitario, para conocer la factibilidad de proyecto para el uso de las aguas residuales de la laguna de oxidación en el barrio Terencio cierra, y al mismo tiempo conocer la opinión de los vecinos que viven a su alrededor 1. ¿Sabe Ud. que aquí existe una laguna de oxidación? ¿Y par que sirve? 2. ¿Qué opinas de la instalación de tratamiento de aguas negras? 3. ¿La instalación le beneficia a Ud. directamente? ¿A la comunidad? ¿Cómo? 4. ¿Hay algún impacto negativo a las personas que viven alrededor de la laguna?

(Marque todos que aplican) • Salud • Ambiente • Aire • Social • Agua

5. ¿Cree Ud. que el agua tratado es seguro o esta contaminado? 6. Cuál es su opinión de uso de las aguas residuales para ser utilizadas en proyectos

de: • Cultivo de verduras, frutas, flores, árboles • Cultivo de peces • Cultivo de plantas ornamentales

5. De donde viene el agua que usa Ud. en la casa: • Llave en la casa • Llave comunal • Pozo en la casa, o comunal


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• Ojo de agua natural • Rió o quebrada • Comprado • Otro

6. ¿De donde viene el agua que tome en casa? • Llave en la casa • Llave comunal Pozo en la casa, o comunal • Ojo de agua natural • Rió o quebrada • Comprado • Otro

7. ¿Qué tipo de servicio sanitario tiene en casa? • Letrina • Pozo séptico • Inodoro conectado al sistema municipal • Ninguna • Otro

8. ¿Qué hace con la basura? 9. ¿Cuáles son los tipos de enfermedades mas frecuentes en su familia? 10. Cuál cree Ud. que son las causas de estas enfermedades: (Circulo todo lo que aplica)

• Aire • Agua • Ambiente • Comida

Parshall Flume Price Quote


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SEEHD (Sustainable

Engineering and Environmental

Health for Development)

sustainable wastewater treatment & reuse · sustainable wastewater treatment & reuse tela,...

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