STATE-OF-THE-ART REVIEW OF COLLAPSING SOILS Science and Technology, 6 (2001) 85-92 ©2001 Sultan Qaboos University Problems of Bacteriological Pollution in Water Wells in Wadi Hadramout Water Project *Salem M. Bin Qadhi, #Saeed Y. Bashir and Taha O. Assaggaf *Department of Mechanical Engineering, Faculty of Engineering, University of Aden, Aden Republic of Yemen, #National Water and Sanitation Authority, Wadi Hadramout, Seiyun Republic of Yemen. مشكالت التلوث البايولوجي في مياه االبار في مشروع وادى حضرموت سالم بن القاضى وسعيد بشير وطه السقاف تعرض هذه الورقة مشكلة تلوث مياه الشرب في مشروع صغير هو واحد من المشاريع النموذجية في المنطقة لتوفير :خالصـة .تفاصيل المشروع كما تبين مشكلة التلوث البايولوجيوتشرح هذه الورقة . المياه لألجيال الحاضرة والقادمة ABSTRACT: This paper presents an existing problem of drinking water pollution for a small project and one of the model projects of drinking water in Yemen, designed to save and preserve good quality water for the present and future generations in the area. The paper gives the details of the project and explains the problem of bacteriological pollution and the steps undertaken to solve the problem. Some of the results for short-term solutions and recommendation for the long-term solutions are also given. KEYWORDS: Collapsible Soils, Identification, Laboratory Tests, Field Tests, Stabilization, Foundation Design. 1. Introduction Yemen is a developing country having a population of about 17 million depending mainly on ground water for drinking. Yemen is suffering from a shortage of water and has witnessed a number of drinking water crises in some large cities . This forced the concerned authorities to give priority to drinking water projects in the country. Among leading drinking water projects carried out in Yemen, is the Wadi Hadramout Drinking Water Project which was studied, designed and carried out by international consultants and contractors. Wadi Hadramout Water Supply Project includes Seiyun, Shibam, Al-Qatin and recently Tarim water supply. The project under study is Seiyun Drinking Water Project which is part of Wadi Hadramout Water Project. Seiyun is the capital of Wadi Hadramout and is one of the historical cities in Yemen. It is situated at latitude 15.580 and 48.470 longitude, 20 km from the famous historical town of Shibam and 25 km from Tarim. Seiyun is gaining importance since it is located near the oilfields of Masila and witnessing development in different fields. Seiyun Drinking Water Project was established in 1985 to replace 14 private projects established sometime in 1960. Presently, Seiyun Drinking Water Supply covers Seiyun, Al-Hawtah and 30 villages with a population of around 84,000. The estimated number of service connections by mid 1997 is 12,000. Seiyun Drinking Water Project (Table 1) consists of the following: • The source of drinking water for the project is the deep acquifer ground water where the shallow aquifer water being used for agriculture, gardening and for the use in mosques. 85 SALEM M. BIN QADHI, SAEED Y.BASHIR and TAHA O. ASSAGAF • 7 boreholes with submersible pumps which abstracts an average of 15,120 m3 /day (Dar Al- Handasah). Two boreholes have been drilled but not yet equipped with pumps (Kingdom of Netherlands). • One main reservoir of 2,700 m3 in Seiyun and 7 small reservoirs distributed in the villages having capacities of 100-200 m3 each. • A standby generator of 400 kVA. • Chlorine treatment plant. • Main network consists of ductile iron, φ 100 − 400 mm with a total length of 85 km and branch distribution network consists of galvanized iron pipes with a currently estimated length of more than 200 km. Table 1: Summary of Seiyun drinking water project (Dar Al-Handasah, Kingdom of Netherlands and NWSA-Wadi Hadramout branch). ITEM SPECIFICATIONS 1. System configuration : Number of water wells 9 of 150-200m depth and of 35-45m water depth Treatment type Chlorine Number of storage tanks 8 Storage capacity(m3) 3700 Number of booster pumps 1 at Al Hawta Length of network (km) 235 Connections 12,000 2. Implementation arrangements : Years of design and construction 1984-1988 Funding agency Arab Bank and IDA 3. Details of wells : Number in use 7, 5 m, cemented Number not operational (and reasons) 2 , 50 m , cemented ( not equipped) Maximum water production capacity(m3/day) of wells in use 15,120 4. Supply Capacity and Consumption : Uncounted for water(%) 37 Demand of existing connections met(%) 89 2. Urban Development Problem of Bactoriological Pollution Yemen’s population growth rate is 3.1%. Due to the problem of population increase like other cities and urban areas in the world, Seiyun town is facing urban development and population growth faster than that in other neighbouring towns and villages with the attraction mainly being the presence of economic administrative activities. Seiyun is divided into four sectors and until recently, the expansion is mainly occurring in the south of the town where the majority of land belongs to the state. Due to several factors and reasons the new housing development extended to wellfield. This urban housing development started growing closer to the wellfield in 1992 and is forming a threat to the extension plans of Seiyun wellfield and increased the risk of pollution of underground water due to the use of soak pits as a draining system for more than 1500 houses of the new housing scheme (Dar Al- Handasah, Kingdom of Netherlands and M.G. Ondrus). Recent studies and analysis revealed that there is bacteriological water pollution in some of the water wells existing in the new housing development next to the wellfield area. This problem has been considered by the water authorities management and a number of actions have been taken with the help of local and international funding agencies and consulting experts. Efforts are being 86 PROBLEM OF BACTERIOLOGICAL POLLUTION IN WATER WELLS made side by side to tackle this problem in short-term and long-term measures and are being implemented. 3. Problem Identification We aim to study the protection of the wellfield of Seiyun water source of phase I of the project consisting of 8 boreholes (1985-1995) and phase II originally planned for 1995-2010, where the number of boreholes of the wellfield is to be increased from 9 to 12 and developing a second wellfield. The problem started when residential units were developed some 150 m downstream of the Phase (1) wellfield. National Water and Sanitation Authority (NWSA), Seiyun Branch, has imposed on these developments the replacement of the percolation pits by watertight septic tanks. Regular water analysis is carried out by NWSA-Seiyun branch. Average chemical analysis of water for the year 1999 for the seven boreholes and for borehole No.4 for seven years showed that the water quality is still within the acceptable standards for domestic use for all boreholes as shown in Tables 2A and 2B (Dar Al-Handasah). Table 2(A): Average chemical analysis results of water for boreholes 1-7 taken at NWSA Laboratory-Wadi Hadramout-Seiyun Branch-taken on 5/3/1999(NWSA-Wadi Hadramout branch). Characteristics Average Result Of Analysis For Boreholes 1-7 For Year 1999 WHO Guidelines Unit Temperature 26.7 °C Color 0.0 15 Units Turbidity 0.0 5 F.T.U PH value 7.7 6.5-8.5 Units Conductivity 827 �S/cm T. Dissolved Solids 529 1000 mg/l T. Alkalinity as CaCO3 240 mg/l T. Hardness as Ca CO3 332 500 mg/l Calcium Hardness as Ca CO3 188 mg/l Mg Hardness 144 mg/l Non Carbonate Hardness as CaCO3 92 mg/l Bicarbonate HCO3 292.8 mg/l Calcium Ca++ 75.2 mg/l Magnesium Mg 39.5 mg/l Chloride Cl- 82 250 mg/l Sulphate SO4 85 400 mg/l Nitrate NO3 3 45 mg/l Nitrite NO2 0.003 0.1 mg/l Sodium Na+ 52.7 200 mg/l Fluoride F 0.0 1.5 mg/l Iron Fe 0.01 0.3 mg/l Manganese Mn+ 0.0 0.1 mg/l Bacteriological examinations of water showed that the water quality is acceptable and within the acceptable standards till the year 1997 (NWSA-Wadi Hadramout Branch). Recent analysis during the period mid-1997 and thereafter showed that some of the boreholes are contaminated by non- 87 SALEM M. BIN QADHI, SAEED Y.BASHIR and TAHA O. ASSAGAF fecal coliforms (Dar Al-Handasah and M.G. Ondrus). Analysis for the seven boreholes in use is given in Table 3. Table 2(B): Chemical analysis results of water borehole No.4 for different years taken at NWSA Laboratory-Wadi Hadramout – Seiyun Branch (NWSA-Wadi Hadramout Branch). Result of Analysis WHO GuideLines Characteristic 1986 1993 1994 1995 1996 1997 1998 WHO Unit Temperature 25 31 24 28 29 26 27 °C Color 3 0.0 0.0 0.0 0.0 1 5 15 Units Turbidity 2 0.0 0.0 0.0 0.0 0.0 0.0 5 F.T.U pH value 7.8 7.9 7.8 7.8 7.9 7.9 7.9 6.5-8.5 Units Conductivity 755 732 723 780 783 768 770 µS/cm T. Dissolved Solids 588 768 462 480 481 491 492 1000 mg/l T. Alkalinity as CaCO3 201 220 216 208 218 230 224 mg/l T. Hardness as Ca CO3 295 294 290 300 288 300 306 500 mg/l Calcium Hardness as Ca CO3 160 200 198 202 206 210 212 mg/l Mg Hardness 135 94 92 98 82 90 94 mg/1 Non-Carbonate Hardness as Ca CO3 -- -- -- -- -- -- 82 mg/1 Bicarbonate HCO3 245.2 268.4 263 254 266 230 273.2 mg/1 Calcium Ca++ 64 80 79 80.8 82.4 70 84.8 mg/1 Magnesium Mg 32.8 22.56 22 24 19.6 21.6 22.5 mg/1 Chloride Cl 87.3 71 74 76 75.6 78 78 250 mg/1 Sulphate SO4 84 30 38 36 42 48 78 400 mg/1 Nitrate NO3 8.3 3.5 2.6 1.4 1.8 0.88 3.96 45 mg/l Nitrite NO2 --- 0.001 0.001 0.001 0.001 0.023 0.006 0.1 mg/l Sodium Na+ 57 26.7 32 23 36.6 40.64 50.9 200 mg/l Fluoride F 0.85 0.001 0.00 0.00 0.00 0.01 0.0 1.5 mg/l Iron Fe 0.04 0.00 0.00 0.00 0.01 0.0 0.1 0.3 mg/l Manganese Mn+ --- 0.2 0.1 0.7 0.2 0.0 0.0 0.1 mg/l Table 3: Boreholes water analysis result specifying starting date for first sign of water contamination with non-fecal coliforms (NWSA-Wadi Hadramout). Borehole No. Date of start of contamination Sign of contamination after analysis 1 28/5/1997 Present 2 28/5/1997 Present 3 28/6/1998 6 colonies 4 25/5/1997 Present 5 28/6/1998 14 colonies 6 21/9/1998 3 colonies 7 21/9/1998 5 colonies Boreholes were disinfected by chlorine solution at different intervals and repeatedly. Most of the boreholes gave a positive response to this method, except borehole No. 4 as shown in Table 4. 88 PROBLEM OF BACTERIOLOGICAL POLLUTION IN WATER WELLS Ready and to b For future Ready and to be equi In use Cordon Sani Area = 1.6 K Restricted Area Upland Area (Jawl) Reservoir BH7 BH6 BH5 BH4 BH3 Figure It should be noted tha (a) Results for typic above 200 they a above tables by th (b) Table 4 results w (c) During sampling By repeating the was within the acce response to the disinf is an indication that controlled. Conseque necessary actions are 4. Engineering Op Chemical and b the quality of water borehole No.4 which behind this pollution closer to the wellfield should be protected a engineering sanitary e BH1 BH1 pped taire m2 Upland Area (Jawl) Old City Housing Area Old City Housing Area New Development Al-Heisi Elarba Housing Scheme (1500 Houses) New Development Yethma Housing Scheme (1500 Houses) BH2BH1 New Development Housing Scheme 1. Actual wellfield protection zone (cordon sanitaire) for Seiyun. t the results given in Tables 3 and 4 are subject to the following remarks: al coliform are given in M.P.N. for colonies range from 20 to 200, and for re referred as TNTC (too numerous to count), (M.G.Ondrus) and noted in the e term present. ere taken after chlorination process and after closing the well for 36 hours. and analyzing there was no sign of residual chlorine present. chlorine disinfection, all the boreholes became satisfactory and water quality ptable standards. From monitoring and studies, it can be noticed that the ection process for the boreholes takes a longer time than the earlier one. This the contamination is progressing and needs to be carefully monitored and ntly, continuous monitoring for the boreholes contamination is performed and taken by the authority. tions to Stop Contamination Threat in Seiyun Wellfield acteriological analyses carried out regularly by NWSA-Seiyun, showed that is still within the acceptable standards except in some boreholes; mainly shows the starting of pollution with non-faecal califorms.The main reason is thought to be the new housing development. The new housing development presents a threat to the water quality on the long run. Therefore, the wellfield gainst this threat. Studies (Dar Al-Handasah) have been carried out and three options are identified, presented and discussed. 89 SALEM M. BIN QADHI, SAEED Y.BASHIR and TAHA O. ASSAGAF Table 4: Bacteriological examination results for borehole No.4 taken at NWSA Wadi Hadramout Branch-Seiyun for the period October-November 1999 (NWSA-Wadi Hadramout). Date Collected Hour Collected Temp.°C Date of Data Analysis Time of analysis M.P.N.T. coliform Conductivity µS/cm 6-10-98 36 36 6-10-98 12:17 Present 735 11-10-98 35 35 11-10-98 11:38 Present 770 17-10-98 35 35 17-10-98 12:17 (5) 770 22-10-98 34 34 22-10-98 12:17 Present 770 26-10-98 35 35 26-10-98 12:17 (5) 770 7-11-98 34 34 7-11-98 12:17 Present 759 15-11-98 35 35 15-11-98 12:17 (2) 770 23-11-98 34 34 23-11-98 12:17 Present 762 5. Option 1: Do Minimum Option (DMO) This option is the first step to reduce the contamination risk. It represents adopting watertight septic tanks to replace the existing soak pits for the localities close to the wellfield indicated in Figure 1. NWSA should take responsibility for the technical, management and service aspects of this option. Unfortunately, this option has numerous disadvantages related to already constructed septic tanks and some logistic matters. BH Restricted Area For future Ready and to In use Sewage Treatment Plant Upland Area (Jawl) Old City Housin Old City Housing New Development Housing Scheme Reservoir BH1 BH7 BH6 BH5 BH4 BH3 BH2 Figure 2. Proposed skelton 90 1 Upland Area (Jawl) g New Development Al-Heisi Elarba Housing Scheme (1500 Houses) New Development Yethma Housing Scheme (1500 Houses) BH1 sewage network for Seiyun. PROBLEM OF BACTERIOLOGICAL POLLUTION IN WATER WELLS 6. Option 2: Cordon Sanitaire The Cordon Sanitaire Option (CSO) consists of creating a sanitized area surrounding the wellfield for a distance of at least 250 m from the closest well and the replacement of the septic tanks of the new housing schemes by a sewerage collection network and a treatment plant as shown in Figure 2. Around 30% of the housing units of around 300 houses falling within the CSO would have to be demolished, as indicated in Figure 1. The protection of the water quality of the wellfield is assured by creating a sanitized zone around it as shown in Figure 2. This option has several requirements such as design and construction of the localities sewerage network and controlling the septic tanks in Option 1 until a sewerage network is constructed. The package treatment plant could then be dismanteled and replaced once the sewerage treatment plant of the town is operational. In this option there is a possibility for reusing the effluent of the package treatment plant for the nearby Agricultural Research Center and for use in the cultivated land. 7. Option 3: Wellfield Protection and Septic Tanks Management This option is in fact a combination of Options 1 and 2 above, constituting the DMO and CSO in which the establishment of a protection area i.e. erecting a surrounding fence at a distance of 250 m from closest well. In addition to the protection area, the protection wellfield zone is to be widenend up to 2500 m. There must be a complete drainage system for the housing, industry, hospitals etc and pesticide and fertilizer applications should be limited. Industrial, animal husbandry and storage of hazardous chemicals will not be allowed. Figure 2 shows the extent of the 2500 m radius restriction area. The requirement of this Option then would be: • Controlling septic tanks as in Option 1 above for a short term until the sewerage network is constructed. • Undertake the master plan study to trace the sewerage skeleton network and identify the proper site for the treatment plant and the impact of the plant on the airport runway. Then, design and construct the complete sewerage system. 8. Brief Discussion of Options and Recommendations • The long-term sustainability of the DMO is questionable as it depends on some requirements that are not possible to achieve. • The Wellfield Protection And Septic tank Management Option represent an improvement on the DMO. Although relatively more expensive, it remains affordable and rapidly implementable. But its feasibility depends on NWSA’s capability. Nevertheless, this option is the safer as it would be hazardous to wait for the soil or water to become polluted before action is taken. • The long term option (Option 3) has the advantage that the population will not be exposed to a health risk or odour nuisance since the treatment plant will not be located in the vicinity of the residential area. Hence, the long-term option is recommended when the necessary funds for implementation become available. 9. Cost Estimate for the Proposed Option The housing development areas concerned by the proposed priority sewage collection network are Yethma and Al-hisi-El-Arbaa housing schemes as shown in Figures 1 and 2. Their ultimate 91 SALEM M. BIN QADHI, SAEED Y.BASHIR and TAHA O. ASSAGAF population capacity is estimated as 7,020 and 12,100 respectively. Their area would correspond to 40 ha and 69 ha. The construction cost of the sewage collection network and the main conveyers has been estimated using the following rates (M.G. Ondrus): 1. Collection network, including manholes US $ 25,000/ha 2. Main conveyors, including manholes and lift station US $ 15,000/ha 3. Service connections, including demolition of existing percolation pits, connection pipes and inspection chambers US $ 12,000/ha Based on an estimated generated sewage flow of 2100 m3/day, and oxidation ditch type of treatment with an effluent quality of 20/30, the cost of the treatment plant is estimated as 1.5 million US dollars. The total add up initial investment and operation and maintenanace millions cost is given in Table 5. Table 5: Investment cost (Dar Al-Handasah),(MILLIONS US Dollars). Item Cost Network 2.726 Conveyance 1.635 Service Connections 1.308 Treatment Plant 1.500 Sub Total 7.200 Operation and maintenance Cost .6145 Total 7.814 10. Steps and Actions Taken by NWSA’S • Continuous monitoring of water quality at wellfield and at different points in the water distribution network. • Regular samples of water are taken ,chemical and biological analysis are done. • Immediate chlorine disinfection is done for water wells that show any biological pollution. • Continuous consultation with consultants in case of any water contamination. • The problem of water pollution have been reported to the higher authorities of NWRA and different funding agencies for funding the project of wellfields protection as given in the different options. • Response for funding the wellfield protection and Seiyun Sanitary System is positive and being negotiated with the higher authorities. References DAR AL-HANDASAH, TARIM and SEIYUN ENVIRONMENTAL IMPACT STUDY, NWSA- Wadi Hadramout Branch, Seiyun – Republic of Yemen, 2. KINGDOM OF NETHERLANDS, DIRECTORATE GENERAL DEVELOPMENT COOPERATION. INSTITUTIONAL STRENGTHENING , Five Years NWSA Branches Preparation Phase, Final Report February,1999. ONDRUS, M.G., 1980. Laboratory Experiments in Environmental Chemistry,Wuerz Publishing Ltd,Winnipeg, Canada. NWSA-WADI HADRAMOUT BRANCH, Seiyun – Republic of Yemen, Internal Interim Reports. Received 4 March 2000 Accepted 1 June 2000 92 ãÔßáÇÊ ÇáÊáæË ÇáÈÇíæáæÌí Ýí ãíÇå� Introduction Table 1: Summary of Seiyun drinking water project (Dar Al-Handasah, Kingdom of Netherlands and NWSA-Wadi Hadramout branch). ITEM Urban Development Problem of Bactoriological Pollution Problem Identification Characteristic Conductivity The long-term sustainability of the DMO is questionable as it depends on some requirements that are not possible to achieve. The Wellfield Protection And Septic tank Manageme The long term option (Option 3) has the advantage that the population will not be exposed to a health risk or odour nuisance since the treatment plant will not be located in the vicinity of the residential area. Hence, the long-term option is recommended when the necessary funds for implementation become available. Cost Estimate for the Proposed Option The housing development areas concerned by the proposed priority sewage collection network are Yethma and Al-hisi-El-Arbaa housing schemes as shown in Figures 1 and 2. Their ultimate population capacity is estimated as 7,020 and 12,100 respectively. Thei The construction cost of the sewage collection network and the main conveyers has been estimated using the following rates (M.G. Ondrus): 1. Collection network, including manholesUS $ 25,000/ha 2. Main conveyors, including manholes and lift station US $ 15,000/ha 3. Service connections, including demolition of existing percolation pits, connection pipes and inspection chambersUS $ 12,000/ha Based on an estimated generated sewage flow of 2100 m3/day, and oxidation ditch type of treatment with an effluent quality of 20/30, the cost of the treatment plant is estimated as 1.5 million US dollars. The total add up initial investment and operation Item Cost Network 2.726 Conveyance 1.635 Service Connections 1.308 Treatment Plant 1.500 Sub Total 7.200 Operation and maintenance Cost .6145 Total 7.814 Steps and Actions Taken by NWSA’S References