Attachment No. 1 - 19GT5026Q0007.pdf

SBU - CONTRACTING AND ACQUISITIONS

Attachment 1 Description/Specifications/Performance Work Statement

Wastewater Collection and Treatment System

I. GENERAL INFORMATION:

The United States Embassy in Guatemala requires professional services and contractor cost proposals to perform wastewater treatment plant maintenance services.

II. PROJECT REQUIREMENTS:

1. The sanitary sewer collection system includes the following

• Sanitary Sewage Manholes Quantity: 19

• Storm Sewer Manholes Quantity: 15

• Oil/water Separators Quantity:2

II. DESCRIPTION OF EQUIPMENT:

The wastewater collection and treatment system includes a biodigester unit and a chlorination system, which together provide primary wastewater treatment and disinfection prior to discharge.

These systems require routine monitoring, limited operational intervention, and periodic preventive maintenance, as well as coordination with specialized service providers for sludge removal and corrective maintenance when required.

Item No. Equipment / Component Description

BD-01 Biodigester Tank

Sealed wastewater treatment tank constructed of reinforced concrete or HDPE, designed for anaerobic digestion of domestic wastewater. Operates as a passive system with no moving mechanical parts.

BD-02 Wastewater Inlet Piping PVC piping that conveys raw wastewater from the collection system into the biodigester.

BD-03 Treated Effluent Outlet Piping

PVC piping that discharges treated effluent from the biodigester to the downstream chlorination system.

BD-04 Sludge Extraction Line Dedicated PVC piping used for controlled removal of accumulated sludge during scheduled maintenance.

BD-05 Sludge Extraction Valve

Manually operated shutoff valve installed on the sludge extraction line to control sludge discharge during extraction activities.

BD-06 Clean-Out / Unblocking Port

Access port with removable PVC plug used to clear obstructions in the sludge extraction line when required.

BD-07 Access Covers / Inspection Ports

Removable covers that provide access for inspection, maintenance, and sludge extraction operations.

BD-08 Sludge Extraction Box Concrete or masonry chamber adjacent to the biodigester that temporarily receives sludge prior to removal by vacuum tanker truck.

CH-01 Chlorinator Unit Device that automatically doses calcium hypochlorite tablets into the treated effluent for disinfection. Includes tablet reservoir, dosing mechanism, and control system.

CH-02 Chlorinator Tablet Reservoir

Storage compartment for calcium hypochlorite tablets;

capacity sized to ensure consistent disinfection between inspections.

CH-03 Dosing Device / Feed Line

Mechanical or gravity-fed system that delivers a controlled amount of chlorine into the effluent line.

CH-04 Access Cover / Inspection Port

Removable cover for inspection of tablet level, dosing mechanism, and proper chlorine operation.

CH-05 Support and Mounting Hardware

Brackets, fasteners, and structural supports securing the chlorinator unit and associated piping.

III. GENERAL REQUIREMENTS:

The Contractor shall provide all labor, tools, and materials required to carry out all maintenance as outlined in this SOW. U.S. Embassy in Guatemala staff may have service manuals for all equipment included in this SOW. If they do not, the Contractor shall assist Embassy Staff in obtaining the manuals.

IV. SCOPE OF WORK - PREVENTIVE MAINTENANCE:

Contractor shall provide all materials, supervision, labor, tools and equipment to perform preventive maintenance. All personnel working in the vicinity shall wear and /or use appropriate safety protection while all work is performed. Any questions or injuries shall be brought to the attention of the Post Occupation Safety and Health Officer (POSHO) immediately. Safety Data Sheets (SDS) shall be provided by the Contractor for all HAZMAT materials. Copies shall be submitted to the COR for approval.

At a minimum, the following work must be done:

General Description of Systems and Components to Be Maintained While day-to-day operation is minimal, proper performance depends on regular inspections, compliance with safety procedures, timely sludge extraction, and appropriate chlorination control.

A detailed inventory of all wastewater system components and equipment to be maintained shall be provided in the Equipment List included at the end of this SOW.

Biodigester Operation and Maintenance The biodigester is a low-maintenance treatment unit that operates continuously without the need for daily operational adjustments. Under normal operating conditions, routine operation is limited to inspection and annual sludge removal, unless abnormal conditions arise.

Sludge Extraction Procedure (Annual or as Required) Sludge extraction shall be performed at least once per year, or more frequently if system performance indicates excessive sludge accumulation. The procedure shall be carried out as follows:

Preparation and Safety o Locate the sludge extraction valve, which is housed within a concrete valve box adjacent to the sludge extraction chamber.

o The operator shall wear appropriate personal protective equipment (PPE), including gloves, safety boots, and a protective face mask.

Opening the Sludge Extraction Valve o Slowly open the sludge extraction valve to initiate sludge discharge into the sludge extraction box.

Clearing Obstructions (If Applicable) o If sludge does not flow freely, remove the clean-out (unblocking) plug of the unit.

o Insert a rod or appropriate tool to clear any obstruction in the sludge extraction pipe.

o Once the obstruction is removed, ensure the PVC clean-out plug is properly reinstalled and secured.

Controlled Discharge o Maintain the sludge extraction valve open for a maximum of three (3) minutes to allow sludge to flow into the extraction box.

o After this period, fully close the valve and reinstall the valve box cover.

Sludge Removal by Tanker Truck o The licensed sludge extraction contractor shall immediately insert the suction hose into the sludge extraction box.

o Sludge shall be removed using the tanker truck’s vacuum equipment and transferred to the tanker for proper disposal in accordance with local environmental regulations.

Corrective Maintenance o In the event of persistent flow obstruction at the biodigester outlet or internal malfunction, a qualified plumbing or wastewater service company shall be engaged to perform internal cleaning or corrective maintenance of the unit.

Chlorinator Operation and Maintenance The chlorination system operates using calcium hypochlorite tablets, which dissolve gradually to provide continuous disinfection of treated wastewater.

Routine Operation and Inspection

• The chlorinator shall be inspected weekly to verify the quantity and condition of calcium hypochlorite tablets.

• To perform the inspection, the operator shall carefully open the access box housing the chlorinator and visually inspect the tablets within the dosing device.

Tablet Replacement and Adjustment

• When tablet wear reaches approximately 50% of their original size, additional tablets shall be added to restore the tablet reservoir to its maximum operating capacity.

• During tablet replacement, the operator shall verify that:

o The dosing device is free of obstructions or buildup.

o Chlorine is being properly dosed into the system.

Chlorine Dosage Control

• Chlorine dosage shall be adjusted based on fecal coliform analysis results obtained from the treated wastewater quality monitoring program.

• Adjustments shall comply with the requirements established in the applicable technical study and Government Agreement 236-2006, or any updated regulatory standard in force.

Operator Responsibilities A designated operator shall be responsible for the routine monitoring and control of the biodigester and chlorination systems. The operator’s responsibilities shall include, but not be limited to:

• Periodic inspection and reporting on the operational condition of the biodigester and chlorinator.

• Performing routine control activities to ensure proper system functionality.

• Identifying abnormal operating conditions and coordinating corrective actions with qualified service providers when required.

• Ensuring compliance with applicable safety, environmental, and operational requirements.

Safety and Work Equipment All personnel performing operation and maintenance activities shall be provided with appropriate tools, control equipment, and personal protective equipment (PPE) necessary to perform their duties safely.

At a minimum, personnel shall be equipped with:

• Protective gloves

• Safety boots

• Face masks or respiratory protection, as required

• Basic hand tools for inspection and minor adjustments

• Access to adequate sanitary facilities

Waste Water Collection and Treatment Plant Preventive Maintenance:

V. MAINTENANCE DESCRIPTION:

The maintenance tasks and procedures provided below describe the checks, tests, analysis and tasks required to perform annual, semi-annual and quarterly preventive maintenance for the wastewater collection system and treatment plant.

VI. SAFETY & SPECIAL INSTRUCTIONS:

1. Follow procedures in the O&M Manuals for specific equipment.

2. Follow site safety procedures and your supervisor’s instructions.

3. Record and report any equipment damage or deficiencies.

4. Record maintenance information.

5. Maintenance personnel should be trained on the health hazards of working near sewage plant operations.

6. Maintenance personnel shall be trained, certified, have appropriate equipment and safety plans before and Post approval prior to confined space entry.

7. Follow the manufacturer’s instructions.

8. Wear proper protective equipment.

9. Do not enter the septic tank. Hazards exist in a septic system. All precautions must be followed when inspecting the system. Keep tank openings covered at all times. Only authorized service personnel should service a septic system. Lethal gases, high voltage electricity, and other deadly hazards associated with the system. Only qualified service staff should open access ports and/or covers. Infectious organisms exist in a septic tank. If any contact with wastewater, immediately wash and disinfect all exposed areas and contact personal physician. Failure to do so could result in severe sickness or death. DO NOT use flame or spark near a septic tank access points. Gases emanating from septic tanks can explode if ignited or deadly if inhaled.

VII. MAINTENANCE PROCEDURES:

Listed below are preventive maintenance procedures of a typical wastewater collection system and package treatment plant. The PM frequencies should be evaluated by the Post and adjusted based on local conditions and manufacturer’s recommendations.

Wastewater Collection System

Sewage Collection System Semi-Annually:

1. Storm Drain Manholes. Remove cover, remove mud and debris, examine interior, clean storm outfalls and sediment ponds, clean work area and remove all debris

2. Sanitary Sewage Manholes. Remove cover, observe flow through manhole, remove mud and debris, examine interior, thoroughly ventilate manhole if cleaning is required, clean work area and remove all debris.

3. Oil/Water Separators. Clean out separator, inspect for clogging, scale and improper positioned or missing baffles, and tighten loose parts as necessary, dispose of waste properly.

Wastewater Treatment Plant

Chlorination Quarterly:

1. Inspect the disinfection chamber and tablet chlorinator for proper operation and chlorine contact time.

2. Clean chlorinator and check for leaks

3. Check water trap for proper level and bleed air.

4. Check and clean water strainers

5. Grease fittings

6. Test and calibrate equipment as recommended by the equipment manufacturer.

7. Fill out maintenance checklist and report deficiencies

Semi-Annually:

1. Disassemble and clean the various components of the system, such as meters and floats.

Annually:

1. Inspect and clean valves and springs

2. All tanks, boxes and basins should be drained, inspected for scale buildup, rust, corrosion, and cleaned as necessary. Any painted surfaces should be inspected for rust and corrosion, cleaned and re-painted if necessary

Wastewater Testing and Operating Parameters Monthly:

1. Dissolved Oxygen (DO) Goal: DO = 1.0 – 2.0 mg/L Turn blowers off, and wait 5 – 10 minutes. Take sample from aeration basin and test immediately after sampling. If over the course of several tests during the 2-day maintenance visit, the DO is consistently too low, increase the amount of time that blowers are running. If the DO is consistently too high, decrease the amount of time that blowers are running. The wastewater treatment plant contractor will decrease/increase blower run times by small intervals not to exceed 15-minute increments.

2. Free and Total Chlorine Goal Free Chlorine = 0.5 – 1.5 mg/L

If the plant has a chlorine contact tank, test the effluent being discharged from the plant. If free chlorine residuals do not meet the goals, the wastewater treatment plant contractor will adjust the chlorination rate. If free chlorine readings are consistently above the goal, reduce the amount of chlorination. If the readings are consistently below the goal, increase the amount of chlorination.

3. Chlorine Contact Time Goal CT = 20 mg/L-minutes The wastewater treatment plant maintenance contractor will measure the flow rate of the effluent discharged from the plant at peak hour flows and will calculate the disinfection contact time of the plant (time between injection of chlorine and the discharge of the effluent from the plant). The CT is calculated by multiplying the free chlorine residual (in mg/L) by the contact time. The wastewater treatment plant maintenance contractor will notify the Facility Manager if the CT is significantly less than the goal.

4. Chemical Oxygen Demand (COD) Goal = 50 mg/L

The wastewater treatment plant contractor will sample the plant effluent for Chemical Oxygen Demand (COD). If the COD significantly exceeds the goal, the cleanliness of the plant and the effectiveness of the clarifier weirs will be checked and corrected by the contractor.

5. Total Suspended Solids (TSS) Goal = 30 mg/L

The wastewater treatment plant contractor will sample the plant effluent for Total Suspended Solids. If the TSS readings consistently exceeds the goal, the contractor will increase the frequency of scraping the clarifier and scrubbing the overflow weirs. The contractor will check for proper operation of the clarifier skimmer.