Earth Link and Advanced Resources Development s a. r L. (Elard) Submitted to: Council for Development and Reconstruction


Analysis of Alternatives 4.1Introduction



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4.Analysis of Alternatives

4.1Introduction

This section is based on the alternative schemes presented in the initial EIA report date April 1998 and the updated feasibility study submitted by Montgomery Watson April 2010.

An evaluation of alternative schemes to the provision of a major new water supply source for the Greater Beirut from the Karaoun Lake and Awali Rivers is given hereunder.


4.2No Project Option


Greater Beirut is likely to face serious water shortage in the near future as demand surpasses supply. Climate change may even further exacerbate this problem. If additional sources of water supply are not identified and provided in the near future, the following environmental and socio-economic impacts are expected to arise:

  • Increase pressure on groundwater wells leading to increased salt water intrusion in the coastal aquifers

  • Increased shortage periods of water in Beirut, particularly in the summer period, possibly leading to more conflicts among water users in Greater Beirut

  • Not meeting Millennium Development Goals of access to water

Accordingly, the No Project alternative is considered to be not viable, as it would have severe environmental and socio-economic impacts in Beirut.

4.3Formulation of Options

      1. Constraints


Earlier Feasibility studies of 1972 and 1984 determined that the abstraction and delivery points of the project should be:

  • Abstraction at the construction adit of the Joun HEP plant tunnel prior to the HEP; and

  • Delivery to the southern end of the twin 700mm diameter transmission mains at Khalde (25km to the north) to supply reservoirs in west Beirut.

In addition the feasibility study of 1994 identified a suitable location at Hadath for a new storage reservoir to serve East Beirut and the Southern Suburbs. The location and elevation had to achieve the following requirements:


  • Gravity Feed from Awali to Hadath;

  • Equalizing supply and demand over a period of high consumption;

  • Furnishing water for such emergencies as accidental breakdowns;

  • Supplying water to the northern and southern suburbs, and the Achrafieh reservoirs;

  • Supplying the reservoirs at Tallet El Khayat by a connection to the existing 700mm diameter pipe at Galerie Semaan (in the event of supply shortage) to the existing twin 700mm diameter pipes (one of which is conveying water from the Damour wells); and

  • Providing to regions currently supplied from other sources in case of failure of shutdown of these sources.

The development of the proposed project has been based on these requirements.
      1. Water Transmission Options


Three conceptual options were identified during the various past studies to convey from Joun to Khalde without undue head loss. These are:

  • A pipeline following the hydraulic gradient around the hillsides –knows as the “hillside Route”;

  • A tunnel through the hills following the hydraulic gradient with inverted siphons or pipe bridges to cross valleys as necessary; and

  • A low elevation, high pressure pipeline following the coastal highway (which had already been partially completed as far as Damour and was due to be extended southwards).

The first option was ruled out immediately as being prohibitively expensive. The other two options were carried forward to more detailed considerations in the 1994 feasibility study. The analysis was based on two different routes and the coastal pipeline with three alternative pipeline materials. These are discussed in sections 1.1.39.1 and 1.1.39.2

      1. Water Treatment Options


It was proposed in the 1994 feasibility study that the water treatment should be designed to meet European Union standards as minimum at that date. The new feasibility study (MWH, 2010) revises the treatment process so that the new water guidelines and standards issued by the European Council and also the World Health Organization (WHO) are fulfilled.

The hydraulic head limitations of the project assisted in determining the location and elevation of the WTW.

In the 1994 feasibility study, 4 (four) locations for the WTW were considered, these are – Joun Adit, Jebel es Sarris, Khalde and Ouardaniye.

The fourth site was selected mainly to allow gravity flow through and onwards from the WTW.

The detailed analysis of water treatment locations and treatment options are set out in section 1.1.40.

4.4Detailed Evaluation

      1. Location of Treatment Plant


Four sites were considered in the 1994 Feasibility Study. Their characteristics are summarized in Table 4 -42.

Table 4 42 Characteristics of the four proposed WTW sites



Name

Location

Site Description

Land Area (ha)

Excavation Cost ($M) in 1998


Land Acquisition Cost (1998)

Land Acquisition Cost (2010)

Joun Adit

200m West of Joun tunnel Adit

In a valley with steep slopes and poor access

6.4 – 8.5

25.9 – 35.7


3$/m2

75$/m2

Jebel

es Sarris



1.5km NW of Joun tunnel Adit

Moderate cross slopes with good access but requiring road relocation

4.8 – 6.4

8.3 – 11.4

25$/m2

100$/m2

Ouardaniye

5km NW of Joun tunnel Adit

Moderate cross slopes and good access

4.8 – 6.2

2.3 – 9.4

25$/m2

100$/m2

Khalde

25km north of Joun tunnel


Moderate cross slopes and good access

4.8 -6.3

7.0 – 9.4

110$/m2

500$/m2

All four sites had similar foundation and geological conditions, and would require extensive rock excavation. Approximate excavation costs were estimated in the 1998 EIA report based on required volume and depth of excavation Cost of excavation at Joun and Jebel es Sarris turned be more expensive than that at Ouardaniye and Khalde and thus effectively ruled them out.

Both Ouardaniye and Khalde sites were considered ideally suited for the construction of the WTW.

The Khalde site is ideal in terms of elevation (to suit an entirely gravity project), space, and topography (a reasonably gently sloping site). However, expansion of the city over years has made it relatively expensive in terms of land purchase cost, and plots in Khalde area are being sold for private housing development. The prime benefits of this site are:



  • The close proximity to Beirut where the water is needed; and

  • The reduced risk of pollution of treated water en route from Joun by sitting the plant as close as possible to Beirut.

The Ouardaniye site offers the same essential requirements of appropriate elevation, sufficient area and suitable topography. The prime benefits of this site are that it is:

  • Considerably cheaper than Khalde in terms of current land values (US$100/m2 against US$500/m2);
  • As easily accessible as the Khalde site on completion of the coastal highway; and


  • Able to serve the coastal communities between Ouardaniye and Beirut from the main transmission line between the two. This would be particularly simple in the case of the Pipeline Option and achievable in the case of Tunnel Option 2 (see below) through connection at the Damour Valley and other valley crossings.
      1. Means of Transmission


Tunnel options (see Figure 4 -9) were developed and evaluated to suit potential WTW sites:

  • Tunnel Option 1: Tunnel form Joun to possible Khalde WTW; and

  • Tunnel Option 2: Tunnel from Joun to possible Ouardaniye WTW plus tunnel from Ouardaniye WTW to Khalde

A potential benefit of the pipeline option was that, provided that the water in the pipeline had been treated, it would be comparatively simpler to connect to it for supplies to coastal communities en route to Khalde for treatment, a more expensive site for the works. For topographical reasons a pipeline from Joun to Ouardaniye was impractical; this section must be tunneled. Only one pipeline option was therefore investigated:

  • Pipeline Option: Tunnel from Joun to Ouardaniye WTW plus coastal pipeline from Ouardaniye WTW to Khalde.
        1. Considerations for Tunnel Alignment and Construction

The tunneled options have additional advantages. Tunneling through the hills permits the shortest route towards the end point of the project. The tunnel is also able to follow the hydraulic gradient line with less design constraints, with the exception of deep valley crossings. Due also to the minimum economical size of a tunnel (determined as 2.8m internal diameter in the 1994 feasibility study), the tunneled options also provide additional capacity for any future expansion, and some degree of storage within the tunnel space itself. Most importantly, the tunneled solutions have a significantly smaller surface disruption footprint.

In both tunnel options mentioned above, the alignments were selected to assure, as much as possible, a straight drive on a uniform free-draining gradient in the direction of flow. Both routes deviate eastward from the most direct alignment in order to pass under the many deep valleys, while maintaining a minimum cover of 10m to allow for superficial deposits in the valley bottoms. This also allowed for an adequate safety margin, assuming that a larger tunnel be adopted because of the specific viability of a larger tunnel boring machine (TBM).

Consideration of the construction methods of the tunnels reviewed the options of drill and blast against TBMs. The latter were considered more viable because of the lengths of the drives, because they would give rise to smaller quantities of excavation, and since they would require the use of less concrete for lining. TBM would also enable much more rapid progress to be made, with a consequent overall reduction in the construction time. Drill and blast would only be used in establishing the TBMs in the first 100m of each drive.

Option 1 would give rise to significant quantities of soil at the start of the tunnel drives at the Joun and Khalde with a smaller amount at Damour, whereas Option 2 would result in most spoil at Ouardaniye and Khalde and a lesser amount at Joun and Damour.

The tunnels would be lined with concrete and an impervious membrane to prevent leakage in either direction. The tunnels will be drilled entirely through limestone, some of which is karstic. However, all proposed tunnel sections are above water table and hence groundwater is not expected to cause any problem while drilling. A steel liner with mortar lining was proposed in the shafts and bottom section of the Damour crossing, as well as sections with minimal ground cover (such as the valley crossings and the first and last 100m of horizontal drive from the natural ground surface).

Consideration was given to the need to provide a separate 25mm thick internal lining to the tunnel from Ouardaniye WTW to Khalde in Option2 as it would be conveying treated water. However, the external impermeable membrane already proposed as part of the tunnel structure was considered adequate to prevent infiltration of contaminated water. After initial wetting, any contamination from the concrete itself was considered not to be significant and therefore need for special protection was deemed unnecessary.

Several factors had to be taken into consideration in the tunneled concept, such as the method for crossing deep valleys (pipe bridges, inverted siphons, etc). It was determined during the options development that a tunneled inverted siphon would be best, in order to maintain the integrity of the tunneled solution. The tunnel alignment was adjusted in designs developed in 2001 to minimize the inverted siphon drops.

The alternatives of constructing this crossing using deep trench excavation (involving a river diversion) or tunneling were evaluated. IT was considered unlikely to be viable to set up TBMs for the two short lengths of low level tunnel linking the vertical legs of the siphon to the crossing (only 900m and 400m respectively on north and south sides). Drill and blast were therefore envisaged to be used at this location.

        1. Considerations to Pipeline


The use of the coastal highway as a route for the pipeline from Ouardaniye to Khalde is based on planned provision of service roads on either sides of the main carriageway. Land has already been acquired for these and the pipeline could be located under them without the need for additional land purchase, and without the severe disruption of traffic which construction in the existing carriageway would bring.

The pipeline option has some critical technical disadvantages. These are listed below:



  • Security concerns given that an exposed rural pipeline would be very obviously vulnerable to tampering and intentional acts of damage or foreign aggression;

  • Exposure to damage from Seismic activity given that the pipe route is through seismically active zone;

  • High pressure of the pipelines (+25 bar rating requirement) due to elevation differences could result in very severe consequences in the event of a pipe burst. Any failure in one pipe could damage the adjacent pipe (of the twin pipes), causing complete cessation of service. Pipe failure would also threaten local infrastructure including the coastal freeway and adjacent properties and endanger residents;

  • Extensive expropriations and service corridor requirements particularly given strong urban development especially towards the end of the pipe route; and

  • Aesthetic and Environmental implications due to the extensive construction through rural and natural areas.

Three materials (steel, ductile iron and pre-stressed concrete) were identified as feasible for the use of the pipeline option and were therefore further evaluated by addressing issues such as flow regulation, surge control, leakage control, corrosion and durability, and the different construction methods and operational problems which could result.

Concrete pipes were the cheapest option as they were evaluated taking into consideration the potential for local production. However their bursting failure mechanism (sudden brittle failure) deemed them undesirable for the proposed application. The non-brittle Steel and Ductile Iron pipes proved technically more appropriate given that they would exhibit puncture and leakage type failure mechanisms which could be controlled and would not cause catastrophic failure. Steel & iron pipes therefore adequately address the third point of the disadvantages of pipelines as listed above. They are however, more costly even without considering the cost of extensive expropriations and land acquisition. They also remain vulnerable to the remaining concerns regarding pipeline options.

        1. Access Roads


Based on the proposed use of the TBMs for the main tunnel drives, Option 1 would require the construction of temporary access roads to the working areas at El Labbiye on the southern side of the Damour Valley and to Joun. Access to the Khalde WTW and to the tunnel working site would be via existing roads.

In addition to the upgraded permanent access road to the proposed site of the Ouardaniye WTW, Option 2 would require the construction of access roads to the adit at the low point of the siphon in Wadi Abou Yabes between Joun and Ouardaniye, and to EL Labbiye on the southern side of the Damour Valley. Upgraded existing roads would be used for access to the working sites at the other locations.

The Pipeline Option also required a temporary access road to the adit at the low point of the siphon in Wadi Abou Yabes between Joun and Ouardaniye and an upgraded permanent access road to the proposed site of the Ouardaniye WTW.

Figure 4 9 Altenartive Scheme Options


      1. Water Treatment Process

The ability to achieve a guideline value within a drinking-water supply depends on a number of factors, including:

The concentration of the chemical in the raw water;

Control measures employed throughout the drinking-water system;

Nature of the raw water (groundwater or surface water, presence of natural background and other components); and

Treatment processes already installed (if any).

A qualitative ranking of treatment processes based on their degree of technical complexity is given in Table 4 -43 below. The higher the ranking, the more complex the process is in terms of plant and/or operation. In general, higher rankings are also associated with higher costs.

Table 4 43 Ranking of Treatment Processes

Ranking

Treatment Processes

1

Simple Chlorination

Plain filtration (rapid sand, slow sand)



2

Pre-Chlorination plus filtration

Aeration


3

Chemical Coalgulation

Process optimization for control of disinfection by-products



4

Granular activated carbon (GAC)

Treatment ion exchange



5

Ozonation

6

Advanced Oxidation Processes

Membrane treatment


The approach taken in defining the required treatment process was oriented towards the necessity of treating variable raw water quality due to seasonal changes. During the summer months of dry season the raw water is suitable for direct filtration whereas during the winter months, coagulation, flocculation and sedimentation will be required. For this purpose, the previously proposed design allows this unit to be bypassed and to be fed directly to filtration. Micro-coagulation and flocculation have also been foreseen during direct filtration. The preliminary design report defines the treatment scheme as:



  • Coagulation;

  • Flocculation;

  • Sedimentation;
  • Ozone oxidation (defined to be implemented in the future);


  • 2nd stage coagulation/flocculation;

  • Rapid sand filtration;

  • Final disinfection;

  • pH adjustment;

  • Ammoniation;

  • Sludge to be disposed to the wadi or to the sea;

  • Dirty backwash collection.

The above scheme was revised in the new feasibility study mainly to fulfill the Lebanese standards of drinking water and those of the European Union and the World Health Organization. This is addressed in details in section 1.1.34of the Project Description
        1. Sludge Disposal


An assessment of a wide range of sludge disposal options was made. These are summarized in the following table:

Table 4 44 Sludge Disposal Alternatives

Option

Sub-Option

  1. Marine Disposal

  1. Transport of raw sludge by terrestrial pipeline westwards to the mid-point of Ouardaniye Bay, plus about 2.4 km submarine pipeline to 30m water depth.

  1. Transport of raw sludge by terrestrial pipeline west-south-west to Ras Sahare, plus 900m submarine pipeline to 30m water depth.

  1. Disposal at the Ras Damour Power Station.
  1. Dewatering of raw sludge at the WTW; transport of dewatered sludge by truck to the Power Station and incineration at the latter.


  1. Transport of raw sludge by pipeline to the Power Station; dewatering and incineration at the latter.

  1. Transport of raw sludge by pipeline to the Power Station; injection into cooling water outfall.

  1. Disposal at a nearby cement plant.

  1. Dewatering of raw sludge at the WTW; transport of dewatered sludge by truck to the cement plant.

  1. Transport of raw sludge by pipeline to the cement plant; dewatering and incineration at the latter.

  1. Disposal to local quarries, with possible re-use thereafter.

  1. Dewatering of raw sludge at the WTW; transport of dewatered sludge by truck to the quarry and use is for restoration.

  1. Dewatering of raw sludge at the WTW; transport of dewatered sludge by truck to the quarry. Buffer storage there, with later use in road construction.

  1. Disposal to landfill

  1. Dewatering of raw sludge at the WTW; transport of dewatered sludge by truck to an existing landfill.

  1. Development of a purpose-built contained landfill to accept the sludge. Dewatering of raw sludge at the WTW; transport of dewatered sludge by truck to the landfill.

  1. Disposal to agricultural land.

  1. Dewatering of raw sludge at the WTW; transport of dewatered sludge by truck to the application site. Application by surface spreading.


  1. Transport of raw sludge by truck to the application site. Application by sub-surface injection.

  1. Return the raw sludge to Joun.

  1. Return of raw sludge by pipeline to Joun and injection into the flows upstream of the existing off-take.

  1. Return of raw sludge by pipeline to Joun and injection into Awali River, downstream of the Joun works.


Option D was selected by the designer as the most viable option which is the disposal of sludge to restore local quarries (e .g. the small quarry west of the Ouardaniye WTW) with possible future use of the sludge as a construction material represented the best option for sludge disposal, provided that care will be taken to avoid groundwater contamination. Since this is might still have implications in groundwater quality, it is better recommended to dispose the sludge into engineered landfills.

A detailed consideration of this evaluation is given in Appendix D.

Option Evaluation

From the above discussed options of transmission and treatment plant location, five overall project options were identified Table 4 -45. These were evaluated based on:



  • Cost

  • Security

  • Durability

  • Maintenance

  • Operation flexibility

  • Storage (surplus capacity in tunnel)

  • General environmental impact; and

  • Potential for future expansion.

Table 4 45 Overall Project Options


Option

Option Name

Description

1

Tunnel 1

Tunnel form Joun direct to a WTW at Khalde with pipeline transfer to reservoirs in Beirut

2

Tunnel 2

Tunnel form Joun direct to Khalde via a WTW in Ouardaniye, with pipeline transfer to reservoirs

3

Concrete Pipeline

Tunnel from Joun to a WTW at Ouardaniye thence by concrete pipeline to Khalde with pipeline transfer to reservoirs in Beirut

4

Ductile Iron Pipeline

Tunnel from Joun to a WTW at Ouardaniye thence by ductile iron pipeline to Khalde with pipeline transfer to reservoirs in Beirut

5

Steel Pipeline

Tunnel from Joun to a WTW at Ouardaniye thence by steel pipeline to Khalde with pipeline transfer to reservoirs in Beirut

      1. Cost

It is concluded from the update feasibility study that the cost of the tunnel option project is today at US$ 278.9M, while the cost of the best coastal pipeline option is estimated at US$ 325.5M. These estimates exclude land acquisition costs; however include contingencies, design costs, and site supervision cost. The increase in estimated cost compared to the 1994 estimate can be attributed to the following:


  • Project Scope expansion to include two new reservoirs at Hadath and Hazmieh and associated pipe work.

  • Natural Economic Inflation.

As illustrated above, the tunneled option with WTW located at Ouardaniye remains the most technically and economically superior option at the present time. This is the option selected by the 1994 feasibility study, and which was later progressed to design and tendering in 2001. Many of the same factors that justified this option in 1994 are even more compelling now than they were at the time of the original feasibility study, due to rapid urbanization in the project area over the last 16 years.
      1. Security


In terms of security, a tunnel is less vulnerable than a pipeline and is better able to withstand earthquakes. Although velocity limiting valves will be installed on pipeline to shut down in the event of a major failure, the high pressure at which it would operate poses a damage risk to the highway and adjacent property (as well as to highway users). Supply disruption during emergency repair would be significant. Pre-stressed concrete would be more at risk than steel or ductile iron owing to its greater susceptibility to a sudden burst failure and the fact that the required diameter/pressure combination is on the limit of current manufacturing technology.
      1. Maintenance


A planned internal inspection of the system every five years is envisaged. All options contain a tunnel element, and a planned 2 day shutdown is therefore a common feature. A pipeline is more susceptible to unforeseen maintenance but twinning provides some operational flexibility.

      1. Operational Flexibility

The tunnels for this project cannot be constructed economically at less than about 3m diameter as it is difficult to remove spoil or bring in concrete for the lining with less working space. Hydraulically, the tunnels will therefore be oversized. The spare capacity can, however, be used to advantage as there is shortage of reservoir capacity in Beirut. Alternatively, increasing water demand may eventually necessitate future expansion of the project to supply 9m3/s. the tunnel options will accommodate both these aspects.

      1. Environmental Impact


Environmentally, it was judged in the feasibility study that the construction of the pipeline option would have a greater adverse impact than both tunnel options.




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