E1992 v3 THRO~JGHTHE INITIATIVEOF MAYORREPITOPAJARILLO LO ANL) THE SANGGUNIIANG BAYAIV Of: MERCEDES The site was initially visited on 26 Septernbcr 2003 aid then severa! reconnaissance trips and detailed surveys were untiertaken lasting up to 15 Novernber2003. 1.4 PROJECT LOCATION AND RELATIVE DISTANCES 1.4.1 General The Colasi river, where a proposed mini-hydro power systern will be situated, is located about forty (40) kilometers southeast (SE) of Daet, the capitol town of the Province of Camarines Norte. Figure 1-1 shows the locationmap. 1.4.2 Specific Eocation of Primary Scheme The proposed project site is located w i t b the political boundq of Mercedes Municipality. The proposed diversion dam is situated at 13' 55' 12' latitude and 123"03' 04' longitude. Similarly, the power plant site is located at 13' 03' 37' latitude and 123" 50' 49' longitude FIGURE 1-1 PROJECT LOCATION MAP CHAPTER 4.0: WATER RESOURCES 4.1 WATER SOURCE DESCRIPTION The mini-hydro site is located at the upper reaches of the Colasi river draining the west-east slope of Colasi mountains. The mini-hydro site is situated on a mountainous area. The watershed cover consisting of relatively thick second growth forest trees and undergrowtfis is classified as generally in good hydrologic condition. Srnail expanses of relatively flat grounds are pianted to upland rice, com and vegetab1es. The river and tributary system is classified under youthful development stage. The channels are characterized with tlie presence of deep v-shaped valleys, steep slopes,rapids and waterfalls. The delineation of the watershed area is shown figure 4-1 based on a best weir location of Elev. 280 rneters (rn) above mean sea level. On the bas~s.of this level, the calculateddrainage area is: WATERSHED AREA =9.3 Km2 Page 4-1 4.2 hlYDRQMETEOROLBGICALCHARACTETUSTICS The area falls under type II climate. This climate type is characterized by no district seasons with very pronounced maximwn rainfall fkom October to J a n u v and no dry season. Nomally under ths type, r d a l l is fairly well distributed throughout the year The following is a s m a q of climactic conditions at the projeçt site: Area Climate Classification .............. Type I1 Normal Dry Periods........................ No pronoimced dry season Normal Rainfall Period................... Fairly distribiited yearly with pronounced maxirnum ramfa11 fiom October to Jan. Mean Maximum Rainfall (Dec.)......... 598.8mm. Mean Minimum Rainfall (March)....... 147 mm. Mean Annual Ramfall ..................... 3311inm. Mean Annual Temperature................ 27.10 "C Referente Data Records.................. PAGASA Weather Bureau TGhe figures shown in subsequent pages fiirtl~er illustrate the Iiydrometeorologicalcharacteristicsof the project area. These are: Figure 4-2 : Typical graph of type IIclimate for the entire Plclippines Figure 4-3 : Mean Monthly and Annual Ramfall Depth Figure 4-4 : Rainfall-Intensity-FreqiiencyDuratioa Data tmF) Page 4-2 - ',.- I I C . i Diversioil Weir at Elev. 280 mas1 FIGURE 4-1 FTr,STERSIIEDAREA Pape 4-.? CHAPTER OS: PLAN OF DEVELOPMENT 5.1 CIVIL WORKS SCNEMATIC S. 1.1 General Plan of Development Civil works consist of the constmction of the intake weir: headrace canal, strge ta&, penstock, powerhotise, and aitxiliary siipport stmctiires. The general plan of developrnent is shown in Figtrres 5-la to 5-1c. Based on the geological and water resoilrce considerations as explained in the foregoing chapters, the proposed weir site is located at El. 280.80 meters (rn) The proposed headrace rotite wiil be at the 1efi bank of the river (fookuíg tipstrem). The tailrace leve1 at the proposed power pfant site was set at El. 125.00 based on the tailwater sating c111-veAdditional details of the varioiis scheii-ic of the plant instaifation are presented in the outltne drawings of Figures 5-2 through 5-8 S. 1.2 Wcir Structure The type of weir will be an ogee crest concrete overflow nin-off-the- river type stnichire, hoiilder core with concrete binder and wearing surface, complete with sluiceway, headrace, intake? hydraulic gates, and other apprirtenant stnichires as show-~in Figures 5-33 and 5-3h Page 5- 1 For preliminary design due to seisnuc load, an acceleration of 0.15 is assumed. The weir salient features are as follows: Heigbt.......... .... 1.80m. Crest Leligtla...... ........ 17m. Dam Base Width..... .... 6.0 m. Crest Elevation.......... El. 280.80m. Type................... ... Overflow Type Location .... Colasi River 5.1.3 Headrace 'The headrace wilI be a fiberglass reinforced pipe (FRP) ninning fiom the weir's intake through hillside cuts in a fairly uniform gradient parallel to the river up to the location of the surge tank and the penstock. It is designed based on a d o m flow of 0.58 cu.m./sec (cms) and is shown on Figures 5-1a to 5-1c. 'The rnain features of the headrace canal are as follows: Tqpe ........... ... Conduit with removable cover Length .......... ... 1,980metexs Dimensions ... Q.70m.I.D. Slope. . . . . . . 9.0055 Along the headrace alignrnent where gullies or depressiori are encountered, provisi011 of supplementary water crossing structures will be considered. 5A.4 Surge Tank A surge tank will be located at a comparatively flat area in the rugged terrain. The surge tank will provide: (I) a way where pressure will be released during excessive pressure build-up and; (2) An immediate storage facility of water going to the penstock The main feature of the surge tank are as follows: Type ............................. ......... Johnson's type with outer tank and inner riser .... 3 m. outer diameter by 5 m. depth with riser pipe 0.70m.diameter Reference is made to Figure 5-4 for the details of surge tank 5.1.5 Penstock The penstock, tak'ing off fiom the surge tank is a higb pressure pipeline of FICP material designed to resist the rnaximum bwsting pressure of 156 m. It will be anchored at every major bends where the t h s t due to hydrodynamic pressure is of rnaximurn vaIiie and will De supported at internediate locations by concrete saddte for support. There are two sectron ofthe penstock, narnely Main Penstock a. Material . . . . . .FRP material Length . . . . . 284 m. Interna1 Diameter . . . 0.50 m. b. Branch Penstock Nurnber of Branches ... .... 1 L Material .............. ....... FRP material Length per branch ...... .. 10 m. Diameter per branch ... .. 0.30.m 5.1.6 Powerhouse Refening to Figure 5-6 shows the outline design of the powerhouse. Gross floor dimension of powerhouse is 16.5 by 10.5 meters for a floor area of 168 square meters(sq.m.1. 5.1.7 Service Road An access road will be build from the existing barangay main road to the plant site with distance of about 3 kilometers (km)include a 4.50- meter travei way. 5.2 ELECTRO-MECHANICAL EQUlPMENT AND RELATED WORKS 5.2.1 General The electro-mechanicai equipment and related works mainly covers the generating equipment of tile plant including zppurteriant works and distribution iines. Paçe 5-4 5.2.2 Hydraulic Turbines The proposed maxunurn turbùie discliarge of 0.29 crns. with a net head of 140 m. will yield a maximurn turbine output of 330 KW. The Pelton type of turbines are chosen for the given head/discharge relation. To prevent damages to runner and distributors, these turbines will nomally not be allowed to run below 40 percent of rnaximum discliarge. An optimization of power production and total costs has resulted in the chosen installation of two (2) turbines with identical output of 330-KW each. For the two units, the turbine capàclty sums ta 640 KW. A summary on the data for the turbines are: Type - Pelton Turbine Output 320 KW - Number of Units - 2 Gross Head - 155 m. Net design head - 140 in. Speed of Rotation - 1200 rpm Run-away speed - 2011 rpm . Discharge, Maximum for 2 units -0.58 cms Discharge, per unit 0.20/ unit . - Shafl Orientation -Horizontal Each turbines consists of the following main parts: = The turbine itself consists of the rotating parts the flume part. the guiding cornponents, discharge coinponents, the bearing and tbe governing rnechanism; The rotating part consist of the ninner, tlie rnain shafi, tbe flywheel and the cou'pling; The mam shafi is of horizontal arrangement and rirnnet- of stainless steel buckets; The flurne part consists of the expansion joint. the inlet elbow pipe aod the spiral case; The discharge components consist of the tail elbow tube and the straight conical tube; The main beasing is of íhe enclosed type and lubricated with dilute oil. The lubricating oil is # 32 turbine oil. Cooling water may be drawnfi-omthe special casing. To control the opening of the guide apparatus and to ensure that the unit will ni~isteadiiy at fixed speed under a given load, governor of the singie neglecting fiow-through-type are proposed. The operating voltage is 220 Volts; 60 Hz;3 Phase. 5.2.4 Valve A 0.30-m butterfly valve will Se instaHed at the d e t to each turbine The mode of operation is electrical or manual. The type of connection is ofthe flange me.The control voltage is 220 Volts; 60 Hz 5.2.5 Generator The generating units ~ i l lconsist of w-o (2) horizontal shafi type generators with the following data: Total Plant Output - 600 K W for 2 units GeneratorOutput / Unit - 300 K'N Power Factor - 0 8 1ag Voltage 380 VAC Frequency 60Hz Speed 1200 rpm Cóiuiecilctii - nyt; 1 4 . All ihe two (2) generators will be of tlie three-phase synchronous type directly coupled to the tiirbines through a shafi. The excitation system will be a double windmg sliwit reactor with SCR Regulator. 5.2.6 StepaipTranformer A time-pffase power transformer of 750 KVA rated capacity \vil1 step-up the generator voltage to the line voltage of 13.2 KV. The transformer will be of the outdoor type with oil immersed self cooling md will be supplied with off-load tap chrger (12.58%)on the 13.2 KV line side. It wiH be mounted on a conçrete fouridation outside the powerhouse. 5.2.7 Low Voltage Switchgear The low voltage switchgear will be of the indoor metal clad ciosed cubicle with draw type circuit breakers. It wil! be fiirther equipped with air breaking medium, protective relays, instments meter and synchrosçope. 5.2.8 Auxiliary Service Supply For auxiliary service supply, 3 units of 10 KVA single phase transformer will be supplied for lowering the system voftage fiorn 7620 to 240 VAC. For DC siipply, a 48 volts for controi, proteçtion, emergency & electronic equiprnent wili be supplied The battenes will be equipped with charger 5.2.9 Switcb and Take-Off The 13.2KV take-off wiil be annexed to the power station. The step- up transformer and take-off stnrctims will be located adjacent to the powerhouse. The major configurations are, listed, to wit: Air break switch (ABS), Lighting Anester, êircuit Breakers, Poles, Cross-ms, Tnsulator,Bolts and Nuts, Croundingrod and çouplings. 5.2.10 Control and Protection Pane1 The power station witl be operated from the control and relay room fiom where starhg, stopping and load and voltage control take place. As a protective scheme, the turbine and the voltage regulating system will be designed for automatic operation. Ai1 protection rejays and deviceswiH be located w i h the bdding. Referente is made to figures 5-5 anil 5-8 for the electro-mechanical works schematic dragrarns. Page 5-8 1 1 ( 1 I ' I ~ ~ ~ ..C Z W m I- C*. ..L W C I W SECTION._ 10 - - FIGURIE:5-2: PENSTOCKPRQFILE --- - M E R I O R a d INTERIOR E \ IADOER RUNO DEiNLS FlGCIRE 5-4: SURGE TANK DETAILS SECTiON YHAU '&iI*- :-A< A' -- , - ---- EQUIPMENT ÇPECIFICATION - - . - - .-- -- -- -- - ---. 2 x3WKWTUfWO IMPWLSETURBINE. IYDM NET HEAD. O 24CMSIUNIT *2 x p K W BYNCIIRONQUS GENERATOR. 1200RPM RA'TEO SPEEO EFFiClWY QF NRBINE AT DESIGNE0 POIMT 84 2% iW L D EFFCIENCY OF GENERATOR Bt 0% S0LiRCE PEOPLE'SREPUE)LICQP CHINA FIGURE 5-7: ELECTRO-MECHANICAL DETAILS (Equipment Layout) 'AIR TERMINU W/ MOVMINO t umir a . ai. CARU TO AOD 6nd CABLE TO POST FIGURE 5-8b: ELECTRICAL DETAILS (Sub-Station) CHAPTER 6.0: STABILITY OF GROUND SLOPES 6.1 INTRODUCTION The stability of ground slopes relies on the geological and geotechcal conditions of the pioject area based mady f?om surface geologic rnapping and fiam available geological literatures. Sub-surface investigation such as test pitting md sampling, auger boririg and core dnlling, as necessary, will be undertaken during the detailed enginee~gphase of the study. Such undertahg will define the rock foundation characteristics at the proposed stmctures like weir, powerhouse, headrace and penstock routes. 6.2 REGIONAL GEOLOGY 6.2.1 Physiography Camarines Norte is clustered under the Bico1 sub-province of the Eastem Physiographic Province, which co~istituteone of the bur-(4) physiographic provinces that cornprise the Philippine Archipelago. The classification and division of a physiographic province is based on the island and submarine morphology. Page 6-1 T11c Bico1 sub-province extends fiom Southeni Siena Madre to the southern tip of Rico1 Peninsiila and includes the islands of Polilio and Catanduanes. The Bico1 PeIlmsiila fonns the soiithern parl of LJuzori. Mt. Labo (942 m.)in the northern part of Camarines Norte is one of the dormmt volcmoes along the eastern part. The eastern coast is characterized by very irregular, deep and extensive coastal embayments. The coastal feature of Barangay Colasi? Mercedes, . Camtlranes Norie refle~tsthis general chnracieristic having a deep çoasta.1 embayment witl depth of about 80 meters Pre-cretaceous schist's and quartzite's are tlte basement rocks in tlie regioi~.Th~srock suite is imcon-dortably overlained hy cretaceous to quaternary volcanics and sed~i~~entaryrocks wliich are separateci by either faults or iincomformities. The oldest terti-, sedimentw rocks resting on the nietamorphic md volcanic rocks is the Universal Formation (Meek, etal 1441). This fomztion is intrrided by diorite and related rocks. Tl~eUniversal Formation is vo~npcsedof conglomerate, ar!rose, carbonaceoiis and argillaceous shale ixqd limestone. Later intriision of Larap Volcanics buried the Universal Formation. Subsequent depositiori of the Luurer EvJiocene Bosigoi Formation overlain the Larap Volcanics with an angrilar tmconformiíy. Page 6-2 The lower member of the Bosigon Formation consists of conglomerate, sandstone, calcareous shale and limestone. The upper member is a thick intercalation of basaltic flows, volcanic wackes, tufT breccias, cherts and limestone. Overlying tiie extensive Bosigon Formation in C-es Norte distirict is the Sta. Elena Formation of Late Miocene age. This sedunentary unit is a th~ckinterbedded sequence of conglomerate, sandstone, siltstone, shale and limestone. The project area is believed to be located on the sedimentary units of Sta.Elena Formation and Bosigon Formation. The alluvid deposits consisting of unsorted to pooriy sorted and unconsolidated soil, silt, sand and grave1 along flood plains and large nver valleys cover the northeastern and eastem parts of the province. The alluvial layer includes volcanic debris From Fig. 6-1 (Fold Pattem) Carnarines Norte belongs to the NW-SE system of major folds based on the axial trends. The NW-SE set exhibit axial traces rangmg behveen N45W to NlOW. The most significant normal or gravity fault in the Bico1 rejgon is the NW trending fault in the central part of Camarines Sur that crosses Ragay guif. Thnist faults on the other hand are located in the northeastern parts of Canxines Norte, Carnarines Sur and Catanduanes Island (Miranda and Vargas, 1967). as shown in Frg.6-2- Cnistal Fractures Map of the Philipphes, as modified, in the MGB publication of 1982. Page 6-3 6.3 LOCAL GEOLOGY The project area is on the southeastem coast of CamarinesNorte bounded by San Miguel Bay. Going inland, the topography is characterized by rolling Mls to folded steep valleys or gorges. Low lying rounded peaks have top elevation ranging from 245 meters to 400 meters, while the higliest peak stands at 957 meters wherein the watershed limit is delineated. Local thrust faulting aad folding have developed the steep riverbanks that rises fkom 100 rneters to 400 rneters elevation. The Colasi River, which is the hydro resource, flows through one of the river systems whose gorges could be exploited for a medium length lieadrace distance and a gross head of about 160 meters. The river flows through three (3) waterfallldrops, a11 downstrearn of the weir site. The water falls range in height fiom 20 m to 40 m. Outcrops of sedimentary rocks consisting of sarid stone, conglomerate and few limestone lined the river bed and river banks. The riverbed is littered with boulders of sandstone and conglomerate and some volcanics. Flat areas observed at the weir site are covered with sandy soil xnixed witll cobbles and boulders. Nong the existing trai1 at right bank facing upstrearn, the soil cover is thin and coinposed of sandy clay with losse weathered rock fiagments. Page 6-4 6.4 ENGINEERING GEOLOGY Geologicai Investigation was limited to surface geologic mapping at the proposed weir site, headrace route and powerhouse site. Sub-surface investigation to determine the foundation characteristics and slope stability as well as the suitability of constniction materiais will be canied out at the detded enpeering Ievel of study wherein the location of the weir, headrace route and powerhouse have already been determined. Rock exposures,however, indicate a stable ground slope condition. Surface geologic mapping was conducted along nver channel fi-ornelevation 280 meters, which is the weir site to the powerhouse site at about elevation 120 meten. 6.4.1 Weir Antake The propused m-of river diversion weir will be founded on the massive sectlmentary rocks. The conglomerate and sandstone exhibit irregular interbedding with traces of limestone layer on top. The width section is about 20 meters. Ríverbed deposits of mostly boulders are scattered along a 100-meter stretch downstream to the first waterfall The width of the river channel narrows downstrearri as the left and nght banks tum steep. Page 6-5 6.4.2 Penstock / Headrace route The penstockheadmce route is behg considered along the lefi bank (facing upstream) of Colasi River because it has a shorter length than Zocating it at the opposite bank. Both riverbanks have relatively steep slopes. However, the right bank (facing upstrem) has a siightíy lesser steep slope but would re@e much longer headrace route and wodd necessitate at least four (4) major waterway crossing súuctures. At elevation 125 meters, where the powerhouse site is proposed, the lefi bank rises at an angle of 75 to 80 degrees to a height of about 50 meters. From thereon, however, the slopes of the left bank becomes gentler, hence, much more convenient than the rigbtbank for the laymg of penstock h e . Further, the LGU plaa to buiid an access road at least up to the powerhouse area, on the left bank The rock foundation along the route is solid mass of sandstone aid conglomerate. Fouradation of the penstock apparently will be on sound rock. Where the ground is very steep, rock bolting may be required. The slope surface are moderately to densely forest with second growth trees that protects the slope fiom potential landslides. With m underlying mass of rock with relatively thùi cover of about a meter, the slopes appear stable. The rock surface does not show any significintdiscontinuitiesof ffactu-ingdue to forest cover. Page 6-6 6.4.3 Powerhouse Site The proposed powerhouse station is located approximately 1,980 rneters downstream of weir site ninning at mild siope downstream running along contour elevation 280 C-) meters. The difference in elevation fiom the weir (elevation 280.80 m.) to the powerhouse (elevation 125 m.) is 155.80meters. The p u n d surface is made up of conglomerate and sandstone cobbles ând boulders with thin veneer of clayey soil of not more than a meter in thickness. The vicinity is fairly covered with trees and bushes and heavy vegetatiori is noted above 20 metersfiom the river level. At detailed engtneering phase, test pitting or auger borings are recommended to probe into the depth and thjckness of the overbruden composed of soil and cobbles/boulders but based on the outcrops,they appear to be h. figh-angled joints are sparingiy seen and spaced at 1 .O to 1.5 meters. Some of tbe joints are open. 6.5 SEISMICITY Seisrnicity of the region.can be assessed from shidies conducted jointly by the Philippine Institute of Volcanalogy (PHTVOLCS) and the United States Geological Society (USGS) in 1994 and pubIished with the btie "Estimates of the Regional Ground Motion Hazard in the Philippines " Page 6-7 The stiidy produced probabilistic gound rnotion hazard contow maps to estimate peak ground acceleration ihat have 10 % probability of being exceeded in 50 years for rock, inedium soil. and sofi soil site conditions. The estirnates were caiçutated based on data fiom 21 seismic zones tiiat describe the geographic content and íkequency of earthquake ocçwence for lhe majortectonic elementsof the Philippine region. The authors adopted the ground motion attenuation equation deveIoped by Fukushzma ãnd Tanaka in 1990 who assurned tliat regtonal attenuation characteristics between the Western Paçifiç Içland are settings are similar. The attenuationequation is: LOG 10A = 0.41M-LOGio (R=0.032 x10 O 4 I M )-0.0034 R + 1.30 Where A =mean peak acceleration, crn!sec2 R =shortestdistancebetween site and fault rupture, &I M =surface wave magnitude ln reference to the ground motion hazard maps, the project area belongs to seismic sourcezone 7.0(Figure6-3) having a peak ground acceleration estimated value of 0.23g (Figure 6-4) with a comesponding retum period of 50 years for the sedimentary rocks.For medium soil, the estimated value is 0.35 g (Figure 6-5) whle peak acceleration for soft soil is almost doubled at 0.65 g (Fig.6-7). 6.6 PHOTOGRAPHS The subsequent paga sliow the surface geologic characteristics in photographs. Photo 1-Downstreamview fiom the weir site showinga mowing river channel and river bed depositsofboulders and cobbles.Note the vegetation on both riverbanks Pholo 2 View ofthe lq waterfail at E1 168 rn Massive bed rock of conglomeratef - sãndstone fining the riverbanks Page6-9 Photo 3 - Another view of the Colasi river with the third falls at EI. 203 meters. also showing nature of river bed and watercourse *. Photo 4 - Another view of the proposed headrace route uphill OS the exposed rock surface Page 6- 10 FIGURE 6-1 Fold Patterns FIGURE 6-2 Crusta1 Fractures Page O- 12 FIGURE 6-3 Seisrnic sowcezones and ingdeled faults seismic sowce zones are labeled 1 through 2 1 for referente in r11e text and in Table 1. Dark shading indicated dippi~g-planeseismic sources that are uçed to model the shallow plate interfaces of subdu~ti~ii. Page 6- 13 FIGURE 6-4 Map showing peak horizontal acceleratioil amplitudes in rock for the Philippine region. Acceleratiori values have a 10 percent probability of exceedance in 50 years. Contours are in terms of FIGURE 6-5 Map showing peak horizontal acceleration amplitudes in medium soil for the Philippine region. Acceleration values have a 10 percent Probability of exceedance in 50years. Contotirs are in terms of the acceleration of gravity (G). Page 6- 15 FIGURE 6-6 Map showing peak horizontal acceleration arnplitiides in soft soil for the Philippine region. Acceleration values have a I O percent probability of exceedance in 50 years. Contours are in terrns of the accelerationof gravity (G). Page 6-16