-7M ^- -- -T-,A0. COTABATO...In the other three cities of medium size (Cotabato City, Calamba and Dagupan City), current population estimates are close to 200,000. While the scale

Republic of the PhilippinesLocal Water Utilities Administration

SEWERAGE AND SANITATION PROJECTWATER DISTRICT DEVELOPMENT PROJECT

WORLD BANK

r ',* r o -.. ~~Th~t 0 7~~ ENVIRONMENTAL

ASSESSMENTuro~~~~ ~~~ REPOaRT '

Cr

Republic of the PhilippinesLocal Water Utilities Administration

SEWERAGE AND SANITATION PROJECTWATER DISTRICT DEVELOPMENT PROJECT

ml.w) WORLD BANK

ENVIRONMENTALASSESSMENT

LU2'ON REPORT

COTABATO CITY

OF9ISArAS

MINDAHAO

co 7'0~~

CO TA BATOCITY

July 1997

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY 1

Chapter 1 INTRODUCTION 12

Chapter 2 BASELINE ENVIRONMENT - COTABATO CMTY 16

Section I Existing Environment 16Section II Environmental Pollution 18

Chapter 3 PROJECT DESCRIPTION ANID ANALYSIS OF ALTERNATIVES 25

Section I Project Rationale and Objectives 25Section II Sanitation 25Section m Overall Sewerage Scheme 28Section IV Recommended Project Design for Cotabato City 40Section V No Project Scenario 44

Chapter 4 ENVIRONMENTAL IMPACTS 45

Section I Beneficial Impacts of the Project 45Section II Project Implementation Impacts 47Section III Summary 50

Chapter 5 ENVIRONMENTAL MANAGEMENT PLAN 51

Section I Mitigation Plan 51Section II Monitoring Plan 53Section m Implementing Arrangements 54

Appendices

1. Bibliography2. Climatological Normals (1961-1995)3. Typical Noise Emissions of Construction Equipment4. Expected Noise Levels at Various Distances from Construction Equipment5. Environmental Quality Standards For Noise Maximum Allowable Noise Levels6. The Advanced Integrated Pond System (ALPS) of Wastewater Treatment

EnmironmentalAssessmentReport: Cotabato City i

EXECUTIVE SUMMARY

Introduction

In the Philippines, the typical urban area/bulk-up area is characterized by a heavy concentrationof activities, both commercial and industriaL It is also the area where the density of populationis at its highest. These areas are also the sites where the production and consumption of rawand processed materials could be found. Consequently the, pressure on the life supportsystems in these areas are far higher than the suburban and rural areas. Adverse environmentalconditions such as the generation and similarly the discharge of wastes into the environment iscommon in urban and built-up areas. Unfortunately, the amount, type and concentration ofwaste generated exceed the capacity ofthe local environment to absorb and assimilate them.The canying capacity of the life support systems are stretched to the limits. The urgency ofestablishing collection and treatment methods to prevent adverse impacts to the health andwell-being of the residents, and to the ecological systems which sustain them cannot be ignoredand overstated.

Most urban centers in the Philippines rely on individual septic tank systems for thetreatment and disposal of wastewater from domestic and commercial buildings. However,the designs for such systems is often inadequate. Facilities for land disposal of effluentsfrom the septic tanks are generally absent. Hence, the partialy treated septic tank effluentsflow directly into storm drainage systems and other receiving bodies of water, therebyexacerbating an already grave polution situation.

There are several possible options for addressing this problem, including improving thedesign of the septic tank system with the instalation of soil absorption systems. But anenvironmentally sound altemative that is cost-effective and captures economies of scale isto connect individual properties directly to a sewerage system for the collection, treatmentand disposal of the urban wastes.

The provision of a cost-effective centralized wastewater collection, treatment, and disposal isthe primary objective of the proposed Water Districts Development Project. The proposedproject will assist the local govemment units (LGUs) of Dagupan City, Calamba (in Laguna),Cagayan de Oro City, Davao City and Cotabato City, in finding solutions to the problem ofsanitation. Financing assistance will be partly provided by the World Bank (WB) which shallbe conduited through the Land Bank of the Philippines (LBP). Over-all admmiistration will beexercised by LBP's Project Management Office (PMO) with technical support provided by theCentral Sewerage and Sanitation Program Support Office (CPSO) ofthe Local Water UtilitiesAdministration (LWUA).

Environmental Assessment Report: Cotabato City

Better sanitary conditions will thus be achieved in the areas served by the sewerage,drainage and sanitation systems. This will reduce water-borne pollution and water-loggingwithin the cities and in the surrounding water bodies, thereby bringing health benefits tolocal populations. The construction of the systems will protect shallow groundwateraquifers from contamination.

Environmental Assessment Requirements

This Environmental Impact Assessment Report for Cotabato City has been prepared inaccordance with the Presidential Decree No. 1586 otherwise known as the EnvironmentalImpact Assessment Law and Department of Environtment and Natural Resources (DENR)Revised Administrative Order Nos. 36, the Revised Water Usage and Classification/WaterQuality Criteria and Revised Effluent Regulations of 1990 respectively; and World Bank'sOperational Directive 4.01 on Environmental Assessment. The revised Administrative Order36 for Environmental Impact Statement System issued in 1996 is comprehensive and iscompatible with the World Bank's Operational Directive 4.01. It outlines the procedureto be followed by environmental critical projects (ECPs) and projects to be located inenvironmental critical areas (ECAs), in preparing environmental impacts statement(EISs)1. ECP and ECA are defined in the AO. It should also be noted that that localordinances and regulations governing projects of such nature have been taken intoconsideration in preparing this report. Similar EIA reports are being prepared for the other 4cities.

This report has been prepared by a team of local consultants under the aegis ofthe LWUA andthe Cotabato City Government. Much ofthe work relating to the environmental impactanalysis was undertaken as part of the feasibility study done by C. Lotti and AssociatiConsultation with the community is an on-going process. The sanitation component oftheproject will be executed in a participatory manner, and detailed guidelines have been spelledout.

Selection of Priority Cities

The choice of the first batch of Philippine cities for sewerage investments was made afteran initial screening at the national level of urban areas facing the most serious problem ofpollution by untreated wastes. Of the five cities, Davao and Cagayan de Oro represent thelargest class of provincial cities with current population estimates in the range of a millionand half a million respectively. There are several major population concentrations in thecity; each being a source of sewage contamination for nearby surface and ground water.However, the largest volume of sewage is generated by the largest consumers of pipedwater supply; in the Central Business District or Poblacion area. Untreated wastewaterfrom this area has polluted low-lying coastal areas, and basically converted the principalrivers into open sewers. The scale of the pollution problem can be appreciated by the factthat about 90 per cent of the daily water supply of 140,000 cubic meters in Davao city and

This is the termn used by DENR and refers to the standard Environmental Assessment Reportrequired by the World bank as per OD 4.01

Environmental Assessment Report: Cotabato Citv 2

76,000 cubic meters in Cagayan de Oro is being discharged as untreated or undertreatedwastewater. Outside the Poblacion areas, there are pockets of population concentrationspolluting nearby streams, creeks and drainage channels.

In the other three cities of medium size (Cotabato City, Calamba and Dagupan City),current population estimates are close to 200,000. While the scale of urban pollutionproblems are not comparable with Davao and Cagayan de Oro, these cities are locatedclose to environmentally sensitive wetlands and water bodies. In Cotabato city, the urbanarea is actually below the mean sea level, exposing inhabitants to frequent flooding andwaterlogging during the monsoon months. Calamba is located on the shores of LagunaLake, which has experienced a rapid deterioration in water quality over the last twodecades. Dagupan city is close to a large estuarine zone with ecologically sensitivewetlands and fishponds. In each of these cities, Mayors and city officials have recognizedfor some time that unless their complex environmental problems are tackled through astrategic plan of handling waste disposal sustainability of urban growth could be seriouslyaffected.

Overall Project Approach

The proposed project follows a demand-based approach in the sense that facilities will beconstructed only if they conform with the preferences of local stakeholders, and servicesconform to their respective willingness to pay. The stakeholders represent the differenttiers of organizations from the City Council and Barangay (part of the formal LGUsystem), to the more informal purok, neighborhood and household levels. During projectpreparation, the idea of involving communities in the planning process was field-tested inthree barangays of Davao city, and found to be quite successfuL The basic decision-making process is as follows:

For the capital-intensive trunk system, consisting of the main transportationsewers, primary drains and wastewater treatment facilities, the projectdesign and implementation plan has to be approved by the City Council,because the latter is responsible to repay the loan [see Annex 3 of the StaffAppraisal Report (SAR) for the Project on Financial Aspects].

For the feeder system, consisting of collector sewers, secondaly drains and on-sitesanitation facilities, barangays and local neighborhoods will be associatedwith the planning and implementation program. The design criteria havebeen simplified, so that the feeder system can respond to local preferencesand willingness to pay, rather than be bound by any conventional sewerdesign criteria used in industrialized countries. Detailed design will beconducted through a participatory process described in Annex 13 of theSAR

Given the capital-intensive nature of the investments, the proposed project is only theinitial phase of a program to improve the sanitation infrastructure through a strategicplanning approach that involves a mix of on-site and off-site wastewater collection,

EnvironmentalAssessment Report: Cotabato City 3

treatment and disposal. Choice of initial service areas for sewerage has been confined tothe Central Business Districts or Poblacion areas because these are the major contributorsto municipal wastewater pollution. The only exception made is in the case of Davao City,where a second area of high growth prospects (Toril) has also been included on therequest of the LGU.

The project will construct a sewer network that will discharge sewage to a verticallyintegrated pond system designed to treat both sewage and septage. In each of the cities,with the exception of Davao, the treatment site was selected in areas free fromencumbrances.

For the sanitation and drainage components, the entire city has been included in theproject area, with final selections being made on the basis of demand. On-site treatmentsystems through the construction of VIP (ventiliated improved pit) latrines, pit latrines,pour flush toilets and septic tanks will also be constructed if there is demand fromproperty owners. For those properties with uncertain land tenure (as in squattersettlements), the project will finance the construction of communal toilets, to be managedby non-governmental organizations (NGOs) and/or the private sector. The specificlocations of these facilities will be driven by the willingness to pay for the services bybeneficiaries at the barangay level provided of course that these are technically feasible.

Analysis of Alternatives

The recommended solutions for wastewater treatment were arrived at after an intensiveprocess of evaluating alternatives during the project preparation in order to achieve costeffectiveness and acceptabilty. The alternatives considered were anaerobic/facultativePonds, modified lagoon systems and mechanical treatment. The evaluation of alternativesindicated that the modified lagoon systems, despite having a higher operation &maintenance (O&M) costs compared to anaerobic/facultative ponds (as it requiresmechanical aerators and recirculation pumps) was appropriate. The selected option metthe following criteria the effectively:

Minimize overall pond area required

Minimize odor production

Meet DENR effluent quality criteria, including fecal coliform reduction

Minimize sludge production rate

Maximize potential to use surrounding land for recreational purposes

Environmental Assessment Report: Cotabato City 4

Summary Information on Project Cities

Davao Cagayan de Oro Cotabato Calamba Dagupan

Population (1990) 849.947 339.598 127.065 173.453 128.000

Housmg 163,329 47.724 21.581 32.109 21.219

Size of Central 1 000 hectares 400 hecares 120 hectares 95 hecLares 50 hectaresBusmness Distrc(CBD)

Morbidity rateper 595 for 733 for diarrhea 3050 for diarrhea S18 forparasiti 528 forgastro-10.000 from diarrhea(tbird rank (third rank) (first rank) (secmd rank) eateitis (third rank)diseases arnong diseases)

Water bodies at Davao river and al1 Cagayan nver and About 50%0 of city Laguna Lake About 50Y. af cityrisk because of beaches close to adjoining beaches area ceasints of expeiencing area are wetlands.mnumicipal poUution citv not fit for an Macajalar Bay wetlands, fish poids mrnease in turbidity used for fish

recreaticsal unfit for and eisuarine area and rapid farmingpurposes recreat mal aitrophicaucn

purposes because offeaal_________ tcanamination

The urban area/built-up areas in the project cities are characterized by a heavy con-centration of commercial and industrial activities. It is the area where population densityis highest. These areas also represent the bulk of economic activity in the informal sector -such as, the production and consumption of raw and processed food, light manufacturingactivities and retail distribution. A large proportion of piped water supply from the localWater District is also consumed in the Central Business District (CBD). Consequently, thepressure from both solid and liquid wastes in these areas greatly exceed the capability ofthe land and water resources to absorb, assimilate and recycle them.

Cotabato City

Impact During Construction Phase

The implementation of the project and its components is projected to produce onlyminimal adverse environmental impacts. The socio-economic impacts will be beneficial,and will result in a better standard of living for the municipalities and cities concerned. Inthe short-term, the project will provide employment and livelihood opportunities to thepopulation of the surrounding communities through the jobs generated during theconstruction phase. In the long-term, better sanitary conditions will reduce sicknessescaused by water-relatet- problems. Thus an improvement of the existing environmentalconditions is expected. The project will undertake mitigating measures to minimize, or ifat all possible, eliminate adverse impacts.

Environmental Assessment Report. Cotabato City 5

Air Quality. The implementation of the project will result in an increase in the ambientconcentration of suspended particulates in the vicinity of the project site. This would beattributed to dust from land clearing and excavation activities, which expose soil to windand vehicular traffic over unpaved road.

Water Quality. Excavation activities in the project sites could also loosen soils andtransport of these materials to any surface waters, thereby increasing siltation andturbidity.

During the rainy season, surface runoff may increase total suspended solids, and causetemporary stress at the discharge points. However, the impact will be localized, and whenthe vegetative cover returns, impact on the receiving body of water caused by surface run-off will be eliminated.

Noise. The noise impact during the construction stage is expected to be generally minimaland will not require any special noise abatement measure. The treatment plant sites shallhave a setback away from residential clusters, which will definitely provide the necessarybuffer to reduce noise impact during construction of the modified lagoon systems.

During pipe-laying, some noise will be generated due to the construction activities and thetemporary operation of heavy equipment. Noise from breaking concrete pavement andsidewalks may also pose a temporary problenm However, the noise level at the streets isexpected to be within the ambient noise quality standards.

Ecological Effects. As there are no rare, endemic species of flora and fauna in any of theproject areas, project implementation has minimal impact on the terrestrial ecology.Vegetative covers are expected to be cleared, unavoidably, during civil works.

Impacts During Operation Phase

Air Quality. The operation of the wastewater treatment facility will have minimal impacton the air quahty of the area. Aside from the occasional odor nuisance, it is not projectedto have adverse effect at all.

Water Quality. The implementation of the project will be beneficial to the generalenvironment of participating cities and their environs. Discharging of untreated domesticwaste water from the high volume consumers in each city's Central Business Districts intonearby bodies of water would thus be mniimized or eliminated. However, operations andmaintenance failures may result in occasional discharges.

Socio-economic. The provision of sanitation facilities in the project cites wouldundoubtedly benefit the general populace of these areas. The occurrence of epidemic-scale diseases caused by current unsanitary conditions will be reduced. This will result in amore healthy and productive population.

Environmental Assessment Report: Cotabato Cty 6

Sludge Disposal. The recommentded modified lagoon system or vertically integratedpond system of .reatment will require sludge disposal at very infrequent intervals. Thesludge in the anaerobic pond/s remains for an extended period continuously undergoingorganic decomposition. This may take place over a 20-30 year period. One system inoperation in the U.S. has not been desludged in thirty years. Recent testing of this systemhas indicated that the sludge is well-digested and very stable. If desludging does becomedue, arrangements can easily be made with the city environment office for disposal at thesanitary landfill.

Mitigating measures to minimize, or if possible, eliminate adverse impacts will beimplemented. Measures to enhance the existing environmental conditions in the projectsite shall be implemented to maintain the environmental sustainability of the area. Theimplementation of the project will inevitably cause impacts, both adverse and beneficial.

Table 1 shows the potential impacts, risks and the proposed mitigating actions.

Implementation and Monitoring of Management Plan

The PMO, with the assistance of LWUA-CPSO and consultants to be engaged in theproject, would monitor compliance with the ECC and carry out the requisite datacollection. Monitoring reports would be submitted to DENRJEMB and the World Bankperiodically. While responsibility for the various mitigation activities have been identified,the PMO will ensure that the requirements are complied with; in addition, feedback fromcommunities, city officials, NGOs, etc. will be pro-actively sought through the city publicaffairs programs, regular monthly meetings of barangay captains and other methods.Finally, DENR, through its planned PPA system, would also periodically monitor andaudit compliance with the ECC, assisted by independent contractors.

Table 2 summarizes the responsibilities and timetable for the Mitigation Plan.

Environmental Assessment Report: Cotabato Citv 7

Table 1: Mitigation Actions

Construction Phase

Potential Impact & Risks Mitigation Action

l Poor quality of construction . Design and supervision contract will be separated from supplyand installation contract as a means of assuring quality ofconstruction. Works engineers, with a relatively independentsource of information on construction progress, will be hired.

Air Pollution * Careful construction planning and work phasing, specificationsand construction methods to reduce the length of time that the

• Construction equipment and soil is exposed to the environment.vehicles may cause higher * Provision of adequately and properly maintained storage forsuspended particulates, odors and construction materials and equipment.fumes emissions - C02 , CO, NO, . Expeditious and prompt removal of excavated materials or

dredged spoils from construction sites.* Exposure of fine-grain particles to * Regular and adequate sprinkling of water on dust-generating

wind and vehicular traffic will mounds/piles resulting from earthmoving activities and civillikely result in a decrease in air works.quality. . Good housekeeping for aU construction affected areas and

workplaces.* Control of motor vehicle and equipment emissions.* Use of protective gear by all workers.

Water Pollution and Soil Erosion * Provide temporary drainage and storage facilities for excavationsoils, for fuel and oils needed for equipment.

* Siltation * Careful and rational planning of construction and post-construction phases of the project.

* Maintenance of adequate drainage system.

* Noise from operation of construc- * Erect temporary sound baniers around the work sites; avoidtion equipment would be about 70- simultaneous use of heavy equipment; nimit daytime work,SO dBA at 10 m; 50-70 dBA at 30 vehicle speed at 20 kph; regular maintenance of equipment

l m. * Use of appropriate mufflers and sound proofing of construcfionl ~~~~~~~~~~~machinery, equipment, and engines. Use of appTopriate shock-l ~~~~~~~~~~~absorbing mountings for machinery.

l *~~~~~~~~~~ Establishment of buffer zones and noise zones.

* Temporary Disruption of Traffic . To the extent possible, feeder and collection sewer lines will beFlow located along secondary streets.

l Scheduling and increasing input resources so that period of trafficdisruption in primary roads are reduced.

* Coordinate with city traffic management office and the PNPTraffic Management Command

* Clear directional signs and barriers in case traffic rerouting isneeded.

* Public Information campaign.


Operation PhasePotential Impact & Risks Mitigation Action

* Envirorunental hazards due to * Carefully designed post-construction maintenance, contingencyaccidents and man-made or natural and monitoring programs.disasters. * Well designed plan for detection of accident or natural events

* Breakdown or malfimction of the including precautionary and remedial measures to besewer liflt station will increase taken/observed.level of pollution at the Rio Grande * Adequate plans for environmental rehabilitation, clean-up,de Mindanao near the center of the restoration, and disposition of temporary structures and facilitiescity as raw sewage will have to be installed during the construction phase.dumped directly.

Water Pollution . Upgrade laboratory facilities ofthe Cotabato City Water District(CCWD) to be able to undertake wastewater analysis.

* The effluent discharge point of the * Following the bubble concept, wastewater discharged into thetreatment plant may well be Rio Grande de Mindanao River shall, in the long-term, conformaffected by tidal conditions to the water quality standards established by the Department of(estuary). Environrment and Natural Resources as set forth in DAO No. 34

and 35, Revised Water Usage and Classification/Water QualityStandards and Revised Effluent Regulations of 1990,respectively.

* A dispersion/dilution modeling study will be conducted to priorto locating the outfall. Treated effluent discharge into the RioGrande de Mindanao shall be timed based on tidal conditions.The adoption of the ALPS process for the treatment plants shouldresult into attainment of effluent standards.

l Noise would be at about 65-85 * Establishment of buffer zones and noise zones.dBA, principally coming fromseptage trucks unloading at thetreatment plant.

* Odors (organic and sulfur com- . Maintenance of greenbelt zones and vegetation.pounds mainly from the trucks * Provision of landscaped open spaces which will improve theunloading septage) aesthetics in the area by planting the green strips with appropriate

plant or tree species.

Manaeement and O&M ofthe System Institutional:* Management Contract with CCWD which has proven utility

* Poor maintenance of pumps management and operations capacity.* User consultation at detailed engineering design stage to ensure

* Low connections connection.* Sewerage surcharge should be sufficient to provide incentives for

CCWD to maintain system.* Require M&E reporting to the DENR and LWUA* Explore feasibility of BOO/BOT contracts for recreational

activities in unused lands at treatment sites.. Provide adequate training of CCWD and city staff.Regulatorv:. Require compulsory connection for all commercial, industrial

and high domestic water users.* Utilize Public Performance Auditing system being set up by

DENR to monitor adverse impacts.Technical:. Provision of adequate maintenance equipment and spares with

CCWD.

EnvironmentalAssessment Report: CotabatoCitv 9

Monitoring and Implementation Arrangements

Construction Phase

Ambient air quality measurements will be undertaken near construction sites. This will bemostly near locations where sewer network is being laid and treatment plant sites. Whenselecting sites due consideration will be given to sensitive receptors like schools, hospitals,houses etc. Total suspended particulates (TSP) will be measured once a fortnight, for 8 or24 hours, over the construction period.

Noise will measured at the same locations as TSP. Leq and Lg0values will be measured andrecorded.

Operation Phase

Receiving water quality will be monitored by the DENR through its regional officeswhich is monitoring the status of Rio Grande de Mindanao River and estuarine waterquality on a periodic basis. The PMO will collect information on present conditions,observed changes in pollution loads etc. It should be noted that all the pollution load willnot be removed but the proposed sewerage infrastructure will greatly reduce the problem.Once the plan becomes operational, the treatment plant operator, viz-a-vis, the CotabatoCity Water District (CCWD) would be required to set up a laboratory and measure theeffluent quality.

The Treatment Plant Operator will institute a monitoring program to measure effluentdischarges. Daily representative values of PH, 5-day BOD, COD, Total Nitrogen andTotal Phosphorus will be measured during the start-up period. Once the plant operationsstabilize, weekly measurements (24-hourly basis) will be taken.

Quarterly reports showing the trends of effluent discharge and receiving water quality willbe reported to the PMO and DENR Regional Office.


Table 2Summary of Responsibilities and Timetable for the Mitigation Plan

Activity Responsibility Start Completion

Secure ECC clearance from DENR. CPSO-LWUA Decerrber 1996 Septenber 1997

Collect referaence ambient air paraacters Citv PMU. %vith DEN1R Septemnber 1997 June 1998aroutnd the proposed treatment plant sites at regicutal officeproject cities

Ensurethat the bid documents include PM() Januarv 1998 August 1999provLscmas for mitigaticn under the responsibi-hitv of the cmltaaor: review cootrad or's workplans to ensure comphance with en-virinmental mitigaticn plan provisicins.

Traim operators om O&M practice & handlmng PMO and CPSO-LWUA January 1999 June 2000energency situations.

Assess and upgrade the laboratorv facilities of Project City PMU and local March 1998 June 2000the Cdtabato City Water Distict. Water District

Casdiuc use cankstaicus aad infomation Preject City PMU, with January 1998 Jne 2000[ cmiamstx assi5tanceofNGO.

Matitor and report an compliance PMO Bi-amual basis Bi-amual basis

LWtJjc,C7XSUM.DOCF2299-


1. INTRODUCTION

In the Philippines, the typical urban area/built-up area is characterized by a heavy concentrationof activities, both commercial and industriaL It is also the area where the density of populationis at its peak. These areas are also the sites whiere the production and consumption of raw andprocessed materials could be found. Consequently the, pressure on the life support systems inthese areas are far higher than the suburban and rural areas. Adverse environmental conditionssuch as the generation and similarly the discharge of wastes into the environment is common inurban and built-up areas. Unfortunately, the amount, type and concentration of wastegenerated exceed the capability ofthe local environment to absorb and assimilate them. Thecarying capacity ofthe life support systems are stretched to the lmits. The urgency ofestablishing collection and treatment methods which wil prevent adverse impacts to the healthand well-being ofthe residents, and to the ecological systems which sustain them cannot beignored and overstated.

T he provision of a cost-effective centralized wastewater coRection, treatment, and disposal isthe primary objective of the proposed Water Districts Development Project (WDDI). Theproposed project will assist the local governments ofDagupan, Calamba , Laguna, Cagayan deOro, Davao City and Cotabato City, in finding solutions to the problem of sanitation.

Most urban centers in the Philippines rely on individual septic tank systems for thetreatment and disposal of wastewater from domestic and commercial buildings. However,the designs for such systems is often inadequate. Facilities for land disposal of effluentsfrom the septic tanks are generally absent. Hence the partially treated septic tank effluentsflow directly into storm drainage systems and other receiving bodies of water, therebyexacerbating an already grave pollution situation.

There are several possible options for addressing this problem, including improving thedesign of the septic tank system with the installation of soil absorption systems. But anenvironmentally sound alternative that is cost-effective and captures economies of scale isto connect individual properties directly to a sewerage system for the collection, treatmentand disposal of the urban wastes.

Better sanitazy conditions will thus be experienced in the areas served by the sewerage,drainage and sanitation systems. This will reduce water-borne pollution and water-loggngwithin the cities and in the surrounding water bodies, thereby bringing health benefits tolocal populations. In Davao, Cagayan de Oro and Calamba cities, pollution from humanwastes have affected recreational areas, such as beaches and lake front areas. Projectinvestments in wastewater collection and treatment will also have positive benefits interms of improving prospects of saving the remaining beaches for the city residents. The


construction of the systems will protect shallow groundwater aquifers from contamination[particularly in Toril area, in the case of Davao City, where the aquifer underneath is amajor source of the city's water supply system].

Overall Approach of the Proposed Project

The proposed project follows a demand-based approach, in the sense that facilities will beconstructed only if they conform with the preferences of local stakeholders, and servicesconform to their respective willingness to pay. The stakeholders represent the differenttiers of organizations from the City Council and Barangay (part of the formal LGUsystem), to the more informal purok, neighborhood and household levels. During projectpreparation, the idea of involving communities in the planning process was field-tested inthree barangays of Davao city, and found to be quite successfuL The basic decision-making process is as follows:

(a) For the capital-intensive trunk system, consisting of the maintransportation sewers, primary drains and wastewater treatment facilities,the project design and implementation plan has to be approved by the CityCouncil, because the latter is responsible to repay the loan [see Annex 3 ofthe Staff Appraisal Report (SAR) for the project on Financial Aspects].

(b) For the feeder system, consisting of collector sewers, secondary drains andon-site sanitation facilities, barangays and local neighborhoods will beassociated with the planning and implementation program. The designcriteria have been simplified, so that the feeder system can respond to localpreferences and wilingness to pay, rather than be bound by anyconventional sewer design criteria used in industrialized countries. Detaileddesign will be conducted through a participatory process.

Given the capital-intensive nature of the investments, the proposed project is only theinitial phase of a program to improve the sanitation infrastructure through a strategicplanning approach that involves a mix of on-site and off-site wastewater collection,treatment and disposal. Choice of initial service areas for sewerage has been confined tothe Central Business Districts or Poblacion areas because these are the major contributorsto municipal wastewater pollution. The only exception made is in the case of Davao City,where a second area of high growth prospects (Toril) has also been included on therequest of the LGU.

The project will construct a sewer network that will discharge sewage to a verticallyintegrated pond system designed to treat both sewage and septage. In each of the cities(with the exception of Davao), the treatment sites selected are in areas free fromencumbrances.

For the sanitation and drainage components, the entire city has been included in theproject area, with final selections being made on the basis of demand. On-site treatment


systems through the construction of VIP latrines, pit latrines, pour flush toilets and septictanks will also be constructed if there is demand from property owners. For thoseproperties with uncertain land tenure (as in squatter settlements), the project will financethe construction of communal toilets, to be managed by NGOs and/or the private sector.The specific location of these facilities will be driven by the willingness to pay for theservices by beneficiaries at the barangay leveL provided of course that these are technicallyfeasible.

The recommended solutions for wastewater treatment were arrived at after an intensiveprocess of evaluating alternatives during the project preparation in order to achieve costeffectiveness and acceptability. The alternatives considered were anaerobic/facultativeponds, modified lagoon systems and mechanical treatment. In all the five cities, theevaluation of alternatives indicated that the modified lagoon systems, despite having ahigher O&M costs compared to anaerobic/facultative ponds (as it requires mechanicalaerators and recirculation pumps) was more appropriate. Details are available in projectfiles. The selected option met the following criteria the effectively:

(a) Minimize overall pond area required

(b) Minimize odor production

(c) Meet DENR effluent quality criteria, including fecal coliform reduction

(d) Minimize sludge production rate

(e) Maximize potential to use surrounding land for recreational purposes

Environmental Impact Assessment

This Environmental Impact Assessment Report for Cotabato City has been prepared inaccordance with the Presidential Decree No. 1586 otherwise known as the EnvironmentalImpact Assessment Law and Department of Enironment and Natural Resources RevisedAdministrative Order Nos. 36, the Revised Water Usage and Classification/Water QualityCriteria and Revised Effluent Regulations of 1990 respectively; and World Bank 'sOperational Directive 4.01 on Environmental Assessment. The revised Administrative Order36 for Environmental Impact Statement System issued in 1996 is comprehensive and iscompatible with the World Bank's Operational Directive 4.01. It outlines the proceduresto be followed by environmental critical projects (ECPs) and projects to be located inenvirommental critical areas (ECAs), in preparing environmental impacts statement(EISs)'. ECPs and ECAs are defined in the AO. It should also be noted that that localordinances and regulations governing projects of such nature have been taken into

This is the term used by DENR and refers to the standard Environmental Assessment Reportrequired by the World bank as per OD 4.01


consideration in preparin this report. Similar EIA reports are being prepared for the other 4cities.

This report has been prepared by a team of local consultants under the aegis of the Local WaterUtilities Administration (LWUA) and the Cotabato City Government. Much of the workrelating to the environmental impact analysis was undertaken as part of the feasibility studydone by C. Lotti and Associati Consultation with the community is an on-going process. Thesanitation component of the project will be executed in a participatory manner, and detailedguidelines have been spelled out.

LWUAjrCTCHMP7RIDOCA prl 22. 1997 4:26 PM


2. BASELINE ENVIRONMENT - COTABATO CITY

Introduction

This chapter is in two sections. Section I profiles he existing environmental situation inCotabato City and Section II analyses water pollution impacts (historical) of uncontrolledsewage discharge.

Section I - Existing Environment

2.1 Land Resources and Use

Cotabato City is situated in the northwestern portion of Maguindanao Province It lies on theshores of Moro Gulf in the west-central section of the Island of Mindanao. It is bounded onthe northern flank by the Rio de Grande de Mindanao, the Moro Gulf on the west and theTamontaca River in the South. [Figure 2.1]

The City has a total land area of approximately 176 sq.km., of these 51% are classified asagriculurat fishponds and wetlands and the remaining 49% are residentiat commercialindustrial ana institutional areas including parks and open spaces. [Figure 2.2]

Along the banks of the Rio Grande River are located high-density residential development.The slum areas are located near the supermarket, the interior areas of Parang Road, and theinterior areas of Mabini along Manday River. [Figure 2.3]

2.2 Phv ahy and Geology

The city is basically a delta formed by the Tamontaca River in the south and the Rio Grande deMindanao River in the north. It is generally flat and low lying with nearly 90% ofthe total landarea close to mean sea leveL Pedro Colina Hl and the mimako Hill are the highest points withelevations of 60 meters and 46 meters above sea level (masl), respectively. Perennial marshesand ponds as well as the meandering creeks and rivers dominate the topography within its vasttract of plain.

The expansive outwash plain of the Rio Grande de Mindanao River is made up of recentalluvium prinarily composed of beach deposits, sand, gravel and clay. Hills of raised coralreefs, basically limestone and probably remnants of coral islands during the earlier period arelocated within this flat valley. This indicates that the area was once a waterway connected to


the Moro Gulf that was filled by alluvium deposits. This alluvial valley is surrounded on threesides at varying distances by relativelv high mountain ranges mainly composed of limestone andvolcanic rocks. Marine clastics and tuffaceous rocks form the lower hills.

The city has fairly good land suitable for limited agriculural cultivation. The soils, as classifiedby the Bureau of Soils and Water Management of the Department of Agriculture. is dominatedby the Faraon Clay which makes up 80% (14,079 has.) of the total land area. The other typesof soil are the Tamontaca Clay (15% of total land area) and the San Miguel Clay (5% of totalland area).

2.3 Climate

The climate in Cotabato City is Classified as Type IV based on the Modified Corona'sClassification of Philippine Climates. This type of climate is characterized by a relatively evendistribution of precipitation during the year. There are two distinct seasons in the City; the dryseason which starts from November and lasts till April, and a wet season, beginning in Maythrough October. The average monthly rainfall is 79.97 mm with the highest rainfll occurringin the month of June with 118.3 mm. Mean annual temperature is 27.4°C wle the maxiunmtemperature was registered in the month of April at 34. 1°C. The average annual RelativeHumidity is 79% with the month of July as the most humid at 83%. Appendix 2 shows theclimatological normals for Generals Santos City, the nearest PAGASA station to Cotabatocity.

2.4 Hydrology and Water Ouality

The City of Cotabato is bounded on the northem and southem flanks by two major riversystems, the Tamontaca and Rio Grande de Mindanao. These river systems drains into IanaBay. The Rio Grande de Mindanao for al practical purposes functions as the Citys naturaldrainage system, and the receiving body of water for storm, surface runoff and domestic waste.As such the water quality of the river has continually deteriorated. The river, as per DENRstandards is classified as Class C waters.

2.5 Vegetation and Wildlife

The vegetative cover of the proposed site for the wastewater treatment plant is predominantlywild grass interspersed with coconut trees with some portions being planted to rice. As iscommon in most sites near buil-up areas, the floral and fauna communities are highlyinfluenced by the economic activities of the hurman population. The flora and fauna in the areais strictly limited to the requirements of the settlers. Cash crops and domesticated animals arecommon in the area.

2.6 Socio-economic Aspects

As projected based on the 1990 NSO Population Data the population of Cotabato City in 1995was placed at 138,885 persons with a density of 18.46 persons/hectare. The most populous


barangay based on the projections is Bgy. Rosary Heights with approximately 57,506 residents.It is projected that by the year 2015 the population ofthe City will reach 171,058 persons.

Section II - Environmental Pollution

As in most other major cities, the urban area/built-up area in Cotabato City ischaracterized by a heavy concentration of commercial and industrial activities. It is alsothe area where population density is highest. These areas are also the sites where theproduction and consumption of raw and processed materials could be found. Con-sequently, the pressure on the environment in these areas are far higher than the suburbanand rural areas. Adverse environmental conditions such as the generation and discharge ofwastes onto the environment are common in urban and built-up areas. Unfortunately, theamount, type and concentration of waste generated exceed the capability of the local envi-ronment to absorb and assimilate them. The carrying capacity of the life support systemsare stretched to the limit.

2.7 Existing Sanitation Conditions

Informal interviews conducted during the several technical field investigations regardingon-site sanitation facilities reveal that most of the households interviewed were satisfiedwith their existing toilet facilities.

The relatively high degree of reasonable satisfaction with their existing systems suggeststhat heads of households have little concern for the unsatisfactory disposal of these wastesonce they leave the dwelling, but could also relate to how the inquiries were conducted.In any event, it is clear that the present system is far from satisfactory, despite the opinionof the users, because:

About half of the households have inadequate on-site sanitation facilitiesPractically all of the households are disposing of their wastes in a manner whichposes risks to the public health of the people of the City.

2.8 Health Problems Faced by Cotabato City Residents

As in the other project cities, sewage contamination is a prime cause of diarrheal diseasesin Cotabato City. The City Health Office (CHO) maintains records of morbidity andmortality in the City. Among the ten leading causes of morbidity and mortality in 1991,water- related diseases such as diarrhea, typhoid fever and dysentery are ranked first, sixthand eleventh in the list of morbidity, and diarrhea is hsted as eighth, among the causes ofmortality.


2.9 Existing Environmental Conditions of Moro Gulf and Rio Grande de MindanaoRiver

The Regional Office of the Environmental Management Bureau (EMB) under theDepartment of Environment and Natural Resources conducts monitoring of water qualityof Moro Gulf and Rio Grande de Mindanao River. Samples are collected at selectedpoints and are sent to the laboratory for physical and chemical analyses.

The results of the monitoring programs in September 1990, July 1991 and July 1992indicate that Rio Grande de Mindanao River is experiencing oxygen depletion indownstream reaches near the City. Dissolved oxygen (DO) levels range from 6.2 mg/l atthe wharf area in the City to 0 - 0.7 mg/l at Barangay Kalanganan. The EMB allowableminimum DO level is 5 mg/i for Class C rivers such as Rio Grande de Mindanao. Class Crivers are suitable for fishery water for the propagation and growth of fish and otheraquatic resources, and recreational water for boating or related purposes. TheBiochemical Oxygen Demand (BOD) level was 0.8 mg/l at the wharf area and 115 mg/ldownstream at Barangay Kalanganan. EMB sets maximum BOD levels at 10 mg/l forClass C rivers.

The BOD and DO levels indicate that the river is badly polluted in the downstream reach.It is clear that organic pollution from untreated wastewater discharges into the river is theprincipal cause of the adverse environmental conditions.

Water samples collected from Moro Gulf at Parola Beach, Bgy. Kalanganan in July 1992indicated that these waters also suffer from oxygen depletion, with a DO level of 1.9, wellbelow the minimum standard level of 5 mg/L Bacteriological examination of water at thesame beach conducted in August 1992 determined that fecal coliform levels wereexcessive.

2.10 Reduced Opportunities for Commercial Development

Accelerated high-rise construction and sharp increases in property values haveaccompanied the installation of sewerage in the Makati district of Manila and the centralbusiness district of Jakarta, Indonesia. In some Latin American cities, central-cityproperty values are reported to have increased by as much as 20% after sewerage wasinstalled. It would not be surprising to see similar results in Cotabato City if seweragewere installed in the Poblacion district. The city is well-positioned to become acommercial hub for its region, and the city leadership clearly aspires to this role for thecity. Rapid expansion of high-rise commercial activity in Poblacion seems very unlikelyunless the area is served by a sewer system.

2.11 Summary of Findings on the Existing Environment

Environmental conditions in the City are unsatisfactory. Two activities constitute theprincipal sources of pollution:


Excreta and Wastewater Disposal. As noted at the beginning of this Chapter, about halfof the population are without satisfactory on-site sanitation facilities, and most of thewastewater from household with acceptable facilities finds its way into the City's drainsand water courses. These deficiencies aggravate the poor environmental conditions ofCotabato City.

Solid Wastes. Solid wastes are collected only from the Poblacion and its outlying areas andlarge amounts of these wastes are littered casually at the places where they are generated.Much of these wastes find their way to the City's drainage system, hampering the drainsfrom conducting runoff during rains and contributing to flooding and general uncleanliness.Wastes that are collected are improperly disposed of burned and left uncovered at an opendump near residential areas of Bgy. Rosary Heights.

Health-related problems related to sewage contamination are of uncertain magnitude, butare an important consideration for the city leadership. Waterbome and other sanitationrelated diseases continue to be a major public health problem in the country. In 1990 aNSO survey reports that 27% of the total households in Cotabato City have unsanitarytoilet facilities while 16% have no toilet facilities. Morbidity and mortality figures showthat adverse sanitary condition is one of the main reasons why diarrhea ranks number onein the leading causes of diseases in the City. It also ranks eighth among the leading causesof mortality in Cotabato.

Overhung latrines are a familiar sight along river banks and along main drainageinterceptors. In these areas human waste is directly discharged below the structure andabsorbed by the Rio Grande River. Manday River which cuts across the city is similarlypolluted with domestic solid and liquid wastes.

Tlhe health statistics and the existing water quality conditions of the citys water bodiesclearly show that there is a need to address the deficit in sanitation to improve the city'shealth and environmental conditions.

Water qualty monitoring results of DENR Region showed that the permissible hmits onsuspended solids and dissolved oxygen are exceeded for Class C water in Rio Grande deMindanao. The deteriorated water quality of Rio Grande de Mindanao is obviously due tothe proliferation of households constructed along the river without proper toilet facilities.Human excreta are directly discharged into the river, with the people unmindful of thehealth and environmental consequences it may result. Based on the ocular inspectionconducted, the Manday River which runs through the city is similarly polluted. The riverreceives all types of waste, including human wastes from houses constructed along theriver banks.

Pollution of the Moro Gulf is closely related to drainage from the neighboring population.Adverse environment conditions exist in the rivers feeding into the gul£ particularly theRio Grande de Mindanao River, due to organic pollution from untreated wastewater


discharges into them Pollution reduction will then depend on the proportion of the localpopulation whose sewage are treated or safely removed from septic tanks.

As in Davao City and other project cities, fishing productivity, in the gulf waters hasdeclined, but sewage contamnination has not been a significant factor.

Commercial development in the Poblacion is repressed by the absence of sewerage.Installation of a system would permit high-rise construction and a significant increase inproperty values.

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3. PROJECT DESCRIIPTION AND ANALYSIS OFALTERNATIVES

Introduction

This chapters begins with an explanation of the rationale of the proposed project and thengoes onto describe the project. The main components -- sanitation and scheme aredescribed separately. Description includes the analysis of alternatives considered inarriving at the final choice. The chapter concludes with the recommended design and plan.

Section I - Project Rationale and Objectives

Chapter 2 describes the existing environmental situation in Cotabato City, and illustratesthe worsening health impacts caused by the uncontrolled discharge of sewage. There isnegligible piped sewerage in the city. There are no treatment and disposal facilities forseptage removed from septic tanks. Septic tank soakaways and overflows enter the drainsand the groundwater.

The proposed project is, therefore, aimed at addressing the problems of inadequatesanitation and sewerage in the City of Cotabato by providing sustainable sanitation andsewerage facilities, thereby reducing public health risks and environmental pollution fromwastewater sources. The project is designed also to provide a learning experience-forfuture expansion of sustainable sanitation services for the city as well as for other cities.The selection of final project design is driven by: (i) demand-based approach; (ii) level ofwastewater treatment to be achieved; and (iii) the need for protecting the environment.

Section II - Sanitation

Proposed Facilities

The sanitation component will include the construction of 2,200 VIP latrines, 734 pour-flush toilets and 33 commrunal toilets city-wide. The sanitation works were based upon anidentified deficit of sanitation facilities of 48%. The choice between individual andcommrunal facilities will be driven by technical feasibility and demand by key stakeholdersand not by tenure status. Locations of individual as well as commrunal toilets are not

EnvironmentalAssessment Report: Cotabato City 25

defined yet and will depend on the consultation of potential beneficiaries. The areas to beserved by the communal toilets mav include public areas such markets and low-incomesquatters or blighted areas.

The possibility to construct on-site facilities is site specific. As the majority of squattersare located on government owned property, that is. along river banks and shoreline it isunlikely that communal toilets. with on-site disposal will be technically feasible. In theselocations communal toilets will only be feasible if there can be a direct discharge to aproposed sewer. The sizing of the facility is dependent upon the depth to groundwater,the permeability of the ground and the availability and cost of land. The objective is toconstruct the communal toilets in areas where, through public consultation, there is anestablished demand and willingness to pay for the service. Arrangements for constructionand operation could take many forms such as:

(i) City constructs and operates;

(ii) City constructs and contracts out the operations either to a private company or tothe local community the facility is serving through a leasing arrangement;

(iii) Construction and operation contracted through a concession arrangement.

It is recommended that arrangement (ii) be given preference over the others, particularly ifthe local community is willing to operate the facility.

The different arrangements should be examined following consultation between the Cityand users, in order to implement the preferred option. Then following a monitoringperiod, the more successful operation can be repeated. A balance has to be soughtbetween affordability to construct (the quality) and willingness to pay. The facility has tobe made "attractive" to the users and provide the service they require and, therefore, inselecting the option the following aspects should be considered:

- Site - central location to proposed users (designed to serve 250 users, orapproximately more than 40 properties);

- proximity to a proposed sewer line, if any, of the land area required(including for septic tank/soakaway)

- availability of water supply;

- availability of power supply;

- area not prone to flooding.

* Services - need for inclusion of showers/laundry facilities.

* Design - attractive to users;

- clean, odor/insect free;

- well lit; good security;

- facilities designed for intense usage; need to be functional and durable.


Cost Estimates

A. Capital Cost

The capital cost for the sanitation component is as follows:

Facility Cost Beneficiaries(P million) __ _ _ _ _ _

On site facilities 21.38 16,800Communal Toilets- Construction 10.22 8,250- Land

Total 43.86

The construction cost includes 5% physical contingencies. The cost of engineering hasnot been considered on the assumnption that the design and construction supervision can behandled directly by the City's concemed department because of the simplicity of thestructures.

B. Operation and Maintenance Cost

Annual O&M costs for each communal toilet has been estimated at P192,780. This wouldrequire an user fee of about P1.20-1.40 per visit on the assumption of 250 persons usingthe facility twice daily. It is intended that the cost of O&M plus the operator's fee have tobe covered by the users.

Implementation Schedule

It is assumed that the 2,200 VIP latrines, 734 pour-flush toilets and 33 communal toiletswill have to be constructed during four of the 5-year implementation period of the project.Therefore, an average of 550 VIP latrines, 183 pour-flush toilets and 8-9 communal toiletswould be constructed annually including the required time for consultation and design.However the construction of the sanitation component can be extended over the 5-yearproject implementation period.


Section III - Overall Sewerage Scheme

Classification

Sewerage refers to the collection and treatment, at a single location, of water-borne waste(sewage) discharged from individual properties. It includes the collection and treatment of"domestic" sewage only and not for any "industrial" waste discharge.

The sewage is collected and transported through a network of underground pipes, orsewers, to a WWTP, where the sewage is treated to produce an effluent that can bedischarged to a receiving water body (river, sea, etc.). Sewage flows along the sewers bygravity, that is, the pipes are laid at a slope or gradient which is sufficient to ensure thatthe sewage will flow without causing blockage.

To minimize depth of excavation, sewers, generally, should follow the slope of theground, that is, they go downhill. If the depth of a sewer becomes too deep (greater than5 m) a pump station would be used to elevate the sewage, either to another sewer or tothe WWTP. The sewers are divided into two classifications:

- collector sewers - sewers connecting an individual property or group of severalproperties to a sewer located in the street or right-of-way;

* transportation sewers - those sewers receiving the sewage flow from the"collection" sewers and transporting the sewage to the WWTP.

The transportation sewers can be considered as the "main road", with the collector sewersacting as the "feeder roads".

Selection of Service Areas

A. Poblacion

The Poblacion area is considered a priority area for the following factors:

* increasing population density and limitations for on-site sanitation;

* presence of large commercial establishments, and institutions such as schools,universities, coUege, government offices and hospitals;

* health hazard and risk posed by the increasing wastewater flow on the municipaldrainage system;

* high level of urban development with a population density capable of payingwastewater service charge;


* biological degradation of rivers which have been found to be polluted with humanexcreta and positive for fecal coliforms. Disposal of septic tanks effluent to thedrainage system contributes to aggravate this pollution problem

The identified Initial Service Area (ISA) comprises a total of 27 barangays with an area of1.527 has. and a total population of about 122,770 in 1995 projected to increase to about151.210 in 2015. The ISA is bounded on the north by the Rio Grande de Mindanao, onthe west by Barangays Bagua I and Bagua 2, on the east by the Matampay River, and onthe south by the Estero River.

As shown in Figure 3.1, the ISA is subdivided into three stages of implementation.

Stage I Service Area has been outlined to include those areas which can provide thehighest impact in terms of improvements to the environment as well as to the social andeconomic conditions of the City. The areas included are:

* the Pobalcion's center where commercial and institutional establishments, such asuniversities, hospitals, and offices, are located;

* the barangays that are highly urbanized and densely populated adjacent to thePobalcion.

The Stage I Service Area has a land area of 283 has. with a population of about 72,030 in1995 projected to increase to about 77,850 in the year 2002 (starting of operations) and toabout 88,720 in 2015.

The population which will connect to the system has been estimated at 60% of the servicearea population. At the starting of operations, in the year 2002, the system will serveabout 46,710 users, with 8,341 connections, projected to increase to about 53,230 users in2015 with 9,506 connections.

The figure that 60% of service area population will connect to the system is based on theassumption that 85% of the population (year 2015) would be connected to the CCWDsupply system, and of those, 70% would be connected to the sewer. Expansion of thesystem would be dependent upon the number of sewer connections and the sewage flowfrom each connection. The capacity of WW1TPs and pump stations would have to beincreased once the 60% design flow is reached. This may or may not correlate to theactual connected population.


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Potential Treatment Plant Sites

The strategy to identify potential treatment plant sites for Stage I was:

* take advantage on the availability of small parcel of lands with minimal number ofsettlers. if not totally vacant;

* divide the system into smaller catchment areas considering the potential treatmentplant sites, as well as topography and drainage characteristics.

In consultation with the City the following potential sites were identified:

* Rio Grande de Mindanao* Barangay Lugay Lugay* Kakar* Lua-Luan

None of the sites will require relocation of inhabitants. The sites at Rio Grande deMindanao and Barangay Lugay Lugay have no specific use at present. The other sitescomprise of farm land. A land value of P 300/sq.m. has been used for the WWTP sites asindicated by the City Planning Department. However, the Kakar and Lua-Luan sites havenot been considered for Stage I because they are of considerable distance from the servicearea but, as may be necessary, could be utilized in the future for Stages II and m.

Treatment Process Options

For the treatment of sewage to be collected from the Stage I service area, three processoptions were assessed, as follows:

* anaerobic/facultative lagoons;

* modified lagoons;

* mechanical activated sludge.

1. Anaerobic/Facultative Lagoons

This system comprises of two or more ponds in series: the initial anaerobic pondfollowed by facultative pond(s). Each pond is defined as follows:

* Anaerobic Pond - used primarily as a pre-treatment process for high-strengthwastewater. They may be used for septage, night-soil, and high-strengthdomestic sewage. The advantages of using anaerobic ponds are that theyeffectively decrease the land requirements of subsequent facultative andaerobic ponds and the accumulation of large sludge banks in subsequenttreatment ponds is avoided.


* Facultative Pond - are the most common type used for wastewater treatment.Raw wastewater enters at one end of the pond and suspended solids settle tothe pond bottom. Over a period of time, a sludge layer develops that is voidof dissolved oxygen. The bottom sludge decomposes anaerobically. Abovethe sludge layer, the pond has a facultative layer that alternates from aerobic,during daylight hour, to anaerobic at night. The upper layer of the pond isaerobic at all times due to oxygen supplied primarily by photosynthesis andwind action. Facultative pond effluent would have to be further treated forthe removal of suspended solids before discharging to the receiving water tomeet the effluent discharge standards.

The Feasibility Report selected this process for the initial septage treatment facilityand for identifying the land area requirement for the deferred sewage treatmentplant.

The design criteria for the process is as follows:

* Anaerobic Ponds

- Dual ponds; depth of 4.0 m; side slopes of 3:1; rectangular with length of 1. 5to 2 x width.

- Organic loading of 0.3 kg of BOD/day per cu.m of pond volume.- Detention time at least 1.5 days.

- Pond volume to be determined by the higher value.

- Assumed BOD removal for subsequent treatment of 65%.

* Facultative Ponds

- Dual ponds in series; depth 1.5 m; side slopes 3: 1; rectangular shape, withlength 2 x width.

- Organic loading rate of 400 kg of BOD/day per hectare of pond surface area(based on 40 g of BOD per capita and 10,000 persons per ha). Loading rate tobe applied to residual BOD in effluent from anaerobic ponds.

- Detention time to be 6 days, total for all ponds in series.

- Pond volume to be determined by the higher value.

- Estimated BOD removals of 70% of influent BOD (overail BOD removalsestimated at 90%).

While providing a treatment system that has a reduced land take (compared toa complete facultative lagoon system) and utilizes no mechanical equipment,


there are concerns as to its ability to operate satisfactorily. Concerns raisedinclude:

* Anaerobic Pond

- Will produce odors - particularly if sulfates are present in the influent.

- Sometimes difficult to manage if pH varies on the acid side. Processeffectiveness decreases or fails completely. Short detention period tends toreduce buffer capacity. Once the system becomes acid, it must be treated withlime or some other chemical to neutralize the system.

- Removal of sludge required. Frequently depends on severity of the solids -BOD loading and nature of composition (sludge disposal was not addressed inthe Feasibility Report).

- Ability to treat low strength domestic sewage and variable rates of flow.

* Facultative Pond

- Shallow ponds at depths of 1.5 to 1.75 meters subject to turnover because oftemperature variations or wind and wave action. Temperature not as much ofa factor in areas of low fluctuations.

- Anaerobic and aerobic processes tend to be in state of flux and vacillatebetween stages reducing treatment effectiveness.

- Tends to increase land requirements because of the relatively shallow depth.

- Limited detention period will not ensure the removal of fecal coliforms to anacceptable level.

2. Modified Lagoons

The modified lagoon system, [e.g., the Advanced Integrated Pond System (AIPS),see Appendix 6] is a non-structural design which utilizes earthen constructionpractices to simplify and reduce construction costs. The system is designed tooptimize natural biological processes in order to improve treatment effectivenessand reduce power requirements and chemical additives while limiting landrequirements. The design concept is to miimize sludge production, eliminatedaily sludge handling and restrict desludging to a long term 20- to 30-year cycle.

The modified lagoon system is an integrated, multi-stage biological reactor systemtreating municipaL agricultural and industrial wastewater. The reactors may berelatively deep and constructed of compacted earth as open surface pond areas.The biological reactor has discrete and isolated biological zones integrated into a


single unit; a deeper anaerobic cell(s) at the bottom of the reactor, sludge blanketsuspended over the deepened zone and an overlying aerobic zone comprised ofaerobic bacteria, algae and a saturated oxygen media provided by a combination ofalgae and surface aeration.

In many cases the initial reactor is followed by a similar second reactor operatingin series with the provision to recirculate to the first pond depending on conditionsand circumstances. Recirculation lends flexibility and buffer (shock loading)capacity and adsorption abilities with highly variable hydraulic or organic loadingsor where there is a potential for receiving toxic spikes.

The primary facultative pond with an aerobic surface and extremely anoxic internalcells for sedimentation and fermentation is the initial treatment element in the seriestreatment train. In this element raw or screened wastewater is introduced directlyinto the bottom of a relatively deep internal cell(s) wherc settleable solids aredigested anaerobically. The overflow velocity in the cell is maintained at a lowrate such that the suspended solids and BOD5 removal efficiency approach 100 and65%, respectively. These rates are maintained at less than the settling velocities ofhelminth ova and parasite cysts. Consequently, the majority of these organismsremain in the cells and are permanently removed from the effluent. Settled solidsin the anoxic cells ferment to the extent that only ash remains due to the large cellvolume. Hence, sludge removal is seldom required.

The rising gases and upwelling of wastewater from the anaerobic cell pass througha thick anaerobic sludge blanket, that is formed as a result of the fermentationprocess, and remains suspended above the anaerobic celL The hydraulic detentiontime in this anaerobic zone and corresponding rise velocity is variable by designand nature of the waste stream.

Treatment of soluble waste continues in the overlying aerobic zone, comprised ofaerobic bacteria and algae. These organisms are maintained in an oxygenated stateby photosynthesis, recirculation and surface aeration. The nature of the surfaceaeration creates a circular motion over the entire pond surface area which in turnensures an oxygen rich continuity.

Soluble wastewater components undergo aerobic oxidation and furtherdegradation in this zone. Thus, two normally seemingly incompatible biologicalwastewater treatment processes can be made to coexist uninterrupted in the sameearthwork reactor.

The horizontal velocity of the circular motion is reduced over secondary deepenedzones as a result of the added volume, allowing the aerobic solids to settle bygravity into a secondary digester for further decomposition and stabilization. Asludge blanket is formed in this area and remains suspended over this zone. Thesurface aerobic circulation pattern reliably controls odors.


The further function of the isolated reducing anaerobic zones includesdenitrification, precipitation of heavy metals and fractionization of toxiccompounds to a less toxic state.

Seasonal, (temperature) and wind or wave action driven turnovers of the pondsis prevented by placement and design geometry of the internal cells andsuppression of the thermocline. Turnovers are a complex phenomena oftemperature changes, wind action, pond depths and configuration of the ponds.The advanced pond design features and method of cell integration serves tomaintain the integrity of the system thus preventing potential pond turnovers.

Sludge in the anaerobic cell(s) remains for an extended period continuouslyundergoing organic decomposition. This may take place over a 20 - 30 yearperiod. One system in operation has not been desludged in thirty years. Recenttesting of this system has indicated that the sludge is well digested and very stable.

The second pond in the series is similar in nature to the first with the exception thatthe size and number of internal cells differ depending on the design and type ofwaste treated. Recirculation of the highly oxygenated water from this second pondis introduced to the surface of the primary facultative pond to provide an oxygenrich overlay of this pond. This oxygen quickly acts to oxidize reduced gasesemerging from the fermentation cell and thus mitigate possible migrating odors.Algae in the recycled water tend to adsorb heavy metals that may be present in theincoming waste stream. These algae tend to settle in the primary pond. Thus asignificant fraction of heavy metals can be removed from the primary pond effluentin the form of reduced metal sulfides or as attached to algae solids.

The modified lagoon system is proposed and an appropriate treatment method fora variety of wastewater treatment applications. These include normal dischargesas well as variable hydraulic flows and organic loadings, particularly where theremay be limited industrial pretreatment and source control of high strengthunbalanced wastes and toxic and heavy metal discharges. The design elementsprovide for flow equalization, buffer capacity and recirculation capabilities toachieve secondary and advanced treatment for municipalities, agriculture andindustry.

The design criteria for the process is as follows:

* Basic Design: Three ponds in series to meet coliform requirement

Detention period: Primary pond - 5 days

Secondary pond - 3 days

Tertiary pond - 3 days

Note: Could use 4 ponid series with 5,2,2,1 days detention to achieve higherpercenitage coliforn? removal.

* Pond design depths: Primary and Secondary - anaerobic sections - 4 m

- aerobic sections - 3.5 m

Tertiary Pond - 3.5 m

* Supplemental aeration included for circulation and BOD requirements becauseof reduced area requirements.

* Recirculation from Secondary pond to Primary included for mediareinforcement and as a source of oxygen.

* Land requirements low because of short detention and pond depths.

* Combination of anaerobic and aerobic in same reactor improves efficiency.

* Berm width - 3.64 m in all cases.

3. Mechanical Activated Sludge Plant

The treatment plant would be constructed of reinforced concrete tankage andwould have the following major components:

- Inlet Works: mechanical screens; grit removal; flow measurement

- Primary Settling Tanks

- Aeration Tanks

- Final Settling Tanks

- Anaerobic Sludge Treatment

Together with associat..d control building/laboratory, pump stations andmaintenance buildings, partial standby power generation capability would berequired.

Based on intemational experience, mechanical activated sludge plants, althoughrequiring smaller land area, are more expensive than any lagoon system in terms ofcapital as well as operation and maintenance expenditures. Furthermore, skilledstaff is required to operate the plant. Therefore, the construction of a mechanicalactivated sludge plant is not considered a viable alternative for the city.Consequently, design criteria have not been developed.


4. Recommended Treatment Process

A previous feasibility report (CDM, 1994) selected the anaerobic/facultative pondsfor the initial septage treatment facility and for identifying the land arearequirement for the deferred sewage treatment plant. However, the process hasraised concerns as to its ability to operate satisfactorily without upset. In fact,with the reduced detention times, it is unlikely that any reduction in fecal coliformwill be achieved, which is a major requirement for the protection of the rivers andthe gulf. Any upset to the system has the potential for the production of odors.Unless sufficient land is available, large buffer zones between the lagoons andinhabitants should be provided to reduce the level of odor reaching the nearbyinhabitants.

On the other hand, based on international experience, the adoption of mechanicalactivated sludge plants, althnugh requiring smaller land area, will be moreexpensive than any lagoon system in terms of capital as well as operation andmaintenance costs. Furthermore, skilled staff is required to operate the plant.Therefore, the use of a mechanical treatment plant is considered not a viableoption.

The modified lagoon system utilizes mechanical aerators and recirculation pumpsand, thus, has higher O&M costs compared to anaerobic/facultative lagoons.However, the modified lagoon system has the ability to treat variable strengthflow; minimize odor production; meet effluent qualty criteria, including fecalcoliform reduction; and has a minimal sludge production rate. These featuresallow the modified lagoon system to address the concems related to theanaerobic/facultative ponds

As a result of the above analysis, taking into account the quality of effluent aftertreatment, the availability of land as well as capital and operating costs, themodified lagoon system is recommended for all the WWTP to be included in thealtemative schemes identified for Cotabato City.

Comparison of Alternatives

The altemative schemes identified are briefly described as follows:

AlternativeScheme Description

I The system will drain the sewage of the whole area to the WWTP (modifiedlagoon system) located at the Rio Grande de Mindanao site.

2 The system will drain the sewage of the whole area to the WWTP (modifiedlagoon system) located at the Barangay Lugay Lugay site.


3 The system is divided in two areas: the sewage flow of Area North will drainto the WWTP (modified lagoon system) located at the Rio Grande deMindanao site; while the sewage flow of Area South will drain to the WWTP(modified lagoon system) located at the Barangay Lugay Lugay site.

1. Design Assessment of Alternatives

Specific design parameters for the treatment plants to be considered for the threealternatives are as follows:

Alternative WWFP Connected Total Flow BOD LoadingLocation Population (cum/d) (kg)

Rio Grande deMindanao

I - Sewage 53,232 10,274 2,129

- Septage - 130 650

Total 10,404 2,779

Luana-Luang2 - Sewage 53,232 10,274 2,129

- Septage - 130 650

Total 10,404 2,779

Rio Grande deMindanao

- Sewage 6,338 1,223 254

- Septage - -

3 Total 1,223 254Luang-Luas

- Sewage 46,894 9,050 1,876

- Septage 130 650

Total 9,180 2,526

Assumption: - Flow 213 Ulcap/d- BOD 40 g/cap/d- 60% of the population is connected to the sewerage system.- Septage BOD 5,000 mg/I

2. Financial Assessment of Alternatives

To evaluate the alternative schemes a set of construction unit costs were developed on thebasis of costs derived from the Feasibility Report and other relevant studies and data


gathered by the consultant. For fiuther information, reference should be made to theFeasibility Report.Comparison of the three alternatives is as follows:

(i) Capital Cost

Capital Cost of AlternativesFacility (P million)

1 ~~~~~2 3SEWERAGE1. Collection 74.26 74.26 74.262. Propert Comections 81.13 81.13 81.133. Transportation Systen 34.65 32.28 45.414. Pumping Station 17.96 26.75 22.945. Force Mains 0.40 7.62 6.606. Pump Station (Land) 0.13 0.19 0.167. WWTP 43.09 43.09 47.348. WWTP (Land) 24.00 24.00 27.009. WWTP (Resettlement) _ ___Total 275.62 1 289.32 304.84

Notes:

Capital costs include 5% physical contingencies plus 15% for engineering and training.

At a cost per hectare of P261,625 (includes for contingencies, engineering, etc.) asdevelopedfrom two study areas in Davao and Dagupan. Collection sewers proposed are"condominial", that is, they are routed through private property to optimize the sewerlength and minimize cost of connection to the transportation sewer. Property owners haveto be consulted and agree to the condominial sewer design.

3 The cost of a house connection to a sewerfor an existing property, requiring theabandoning of a septic tank, has been estimated at P9,726 (includes for contingencies,engineering, etc.). Assumes 60% of the year 2001 population connected to the seweragesystem.

(ii) O&M Costs

The O&M costs will increase in relation to the number of connections. Annual O&Mcosts have been computed for each alternative from the year 2001 (starting of operation)to the year 2015. The following table shows a comparison of the O&M costs for the year2001 and 2015.

Annual Cost 2001 Annual Cost 2015Alternatives (P million) (P million)

1 3.58 4.792 4.21 5.573 4.52 5.80


(iii) Net Present Value

The above capital and O&M costs have then be used to determine the net present value(NPV) at 15% discount rate. The result of the analysis is as follows;

Alternatives NiPV_______ _______ _______(1F m illion)

1 180.482 200.083 211.43

(iv) Conclusion

The above NPV shows that Altemative I is the most economic (by about 10% over thesecond) and, therefore, is recommended for implementation. The recommendedalternative is for a collection and transportation sewer network, in the Poblacion area,discharging to a single WWTP located at the Rio Grande de Mindanao site. The WWTPwould use the modified lagoon treatment process and would treat both sewage andseptage. The treated effluent would be discharged into the Rio Grande de MindanaoRiver. The treated effluent will meet the discharge standard prescnbed by DENR

Section IV - Recommended Project Design for Cotabato City

Description and ComDonents

The recommended plan will include the following five components: (i) on-site andcommiunal sanitation facilities; (ii) sewerage system in Poblacion; (iii) maintenanceequipment, tools and spare parts for the operation and maintenance of installed sewerageinfrastructures; (iv) institutional support; and (v) drainage facilities.

Sanitation Facilities

The sanitation component will include the construction of 2,200 VIP latrines, and 734pour-flush toilets with septic tanks to benefit 16,430 residents as well as 33 communaltoilets which will benefit about 8,250 residents in the city.

The on-site sanitation facilities include: "VIP latrine and pit" and "pour-flush toilet andseptic tank". The demand for on-site facilities will, therefore, be established by public

Environmental Assessment Report: Cotobato City 40

consultation concerning rented dwellings and owner occupied houses. Communalsanitation facilities to be provided under the project may be either on-site or off-site,connected to the sewerage system, depending on technical feasibility. The choice betweenindividual and communal facilities will be driven by technical feasibility and demand by keystakeholders, and not by tenure status. However, in slum areas and squatter settlements,the demand will be ascertained not only from the tenants, but also from land owners andfrom local government officials representing public interest.

The communal toilets will be constructed in areas where, througha public consultation,there is an established demand and willingness to pay for the service.

Seweraee Svstem

The sewerage system will include: (i) house connections; (ii) feeder sewers for thecollection of wastewater in neighborhoods, puroks and barangays; (iii) trunk sewers andpumping systems for wastewater conveyance from barangays to treatment plants; and (iv)sewage and septage treatment plants.

The connection of properties to sewers will be made under the project in order to ensuregood workmanship and timely connection of households to installed sewer systems.Recovery of house connection costs will be spread over a period consistent with demand.Feeder sewers will consist of simplified and condominial sewers. Where condominialsewers are used, communities will be given a choice between location of the sewers inbackyards and locating them in front of their properties. Simplified sewers will be used fortrunk and main transportation sewers.

A modified lagoon system as in the ALPS treatment process will be used to treat bothsewage and septage. Its principal unit is a deep vertically integrated pond with ananaerobic pond below a facultative pond system. The geometry prevents turnovers,thereby minimizing odor problems as well as sludge accumulation.

The project proposes the construction of sewerage facilities in the Poblacion of CotabatoCity. In the Poblacion, the Stage I sewerage system will cover a service area population,in 2015, of about 88,720 of which about 53,230 (or 60%) will be served.

The Stage I system proposes the construction of a sewer network that will dischargesewage to a single vertically integrated pond system designed to treat both sewage andseptage. The treatment plant is located at the Rio Grande de Mindanao site and thetreated effluent will be discharged to the Rio Grande de Mindanao River.

The system (see Figure 3.2) wiil include the following facilities:

* collection sewers covering an area of 283 ha;

* transportation sewers with a total length of 7,200 m and diameter from 150 to 600mm;


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* two pump stations with a capacity of 3,341 and 13,580 cu.m/d and a landrequirement of 134 and 296 sq.m, respectively;

* a force main with a length of 200 meters with diameter of 300 mm;* a WWTP with a capacity of 10.404 cu.m/d and a land requirement of 8.0 ha;

* a total of 8,341 connections in the year 2001. The additional 1,165 connections upto the year 2015 will be constructed by the CCWD.

Maintenance Equipment and Spares

Equipment will be provided to the Cotabato City Water District including vehicles,machinery and tools needed for proper operation and maintenance of the sewerage andpumping facilities. Spare parts for critical equipment will also be supplied.

It should be noted that the sewerage systems will, after construction, be turned over to theCCWD not only for operation and maintenance but also for construction of additionalconnections. It is envisaged that the cost of new connections will be paid up-front by theusers at the moment they request to be connected to the system. This will surelyconstitute a constraint and may restrain the users from being

Documents

-7M ^- -- -T-,A0. COTABATO...In the other three cities of medium size (Cotabato City, Calamba and Dagupan City), current population estimates are close to 200,000. While the scale