The geological information in this section is mainly obtained from the Feasibility report by Montgomery and Watson (1994) and from Geological maps (Saida and Beirut sheets) developed by Dubertret in 1945 at a scale of 1:50,000, and Lebanon sheet developed by Dubertret in 1955 at a scale of 1:200,000.
The tunnel passes mainly through the upper and the middle Sannine-Maameltein Formation of Cenomanin and Turonian ages respectively. This formation is mainly composed of hard massive limestone and dolomitic limestone rocks. Exposures of this formation cover most of the study area with a total thickness of around 800 m. Only the upper part of this formation is exposed in the study area.
Conformably overlying this formation is the Chekka Formation of Senonian age. It is mainly composed of thinly bedded soft marl and marly limestone rocks. It is mostly exposed in the areas surrounding Joun village.
In the valleys, especially the Damour valley and in sporadic thin exposures, the above mentioned formations are covered unconformably by Quaternary deposits mainly gravel, sand and sandy clay. Those deposits are relatively thin except in Damour valley, were they are predicted to reach a thickness of around 40 m (Feasibility Report, 1994).
Structurally the area is located few kilometers west of the Coastal Flexure which is the possible extension of the Roum Fault (Nemer, 1999). The flexure extends from Chhim in the southern part to Baawerta and Aaramoun in the central and northern parts of the study area respectively. The Flexure has steeply dipping beds which gentles as we approach the study area. The general inclination of the beds in the study area is around 20˚ dipping towards the west.
The tunnel passes through at least 6 secondary scale faults. They are the E-W and WNW-ESE faults. These faults have both vertical and horizontal displacements with disturbed zones of up to 50m. The disturbed zones are of highly fractured and brecciated rocks, with fine grained gauge and red clay material. Examples of these faults are the Damour River Fault, Damour Village Fault, Barja Fault, and Dalhoun Fault. The Damour crossing and Siphon cuts through the Damour Fault zone.
Other tertiary scale faults and fractures are present in the study area but their nature and effect on such structure is not clear. Jointing of such hard limestone rocks is also not clear.
Recent seismic activities have been reported in the area. Evidence of such activity is from Bisri earthquake in the 1956 with an epicenter located 4 km east of Joun village. The calculated magnitude was approximately 5.8 (Feasibility Report, 1994). The expected ground acceleration in the area is approximately 0.2 g (Harajli, 1994).
The Sannine-Maameltein Formation is the major coastal aquifer in the study area. It is karstic in nature with tertiary porosity meaning that groundwater is flowing mainly in fissures, fractures and conduits. There are no permanent springs issuing from this formation except close to the coastal area and mainly below sea level in the form of submarine springs (Feasibility Report, 1994).
The position of the water table is closely related to the base level which is the sea level and it gently rises inland with a mean gradient of 11.5 m/km. The depth of the water table was determined from groundwater wells (Feasibility Report, 1994).
It is believed that the proposed tunnel lays entirety in the vadose zone way above the water table. However, water flowing from the surface in fractures, conduits, channels, caves and fracture zones is likely to be encountered in more than one place along the tunnel with water discharging at a rate of approximately 5 L/s (Feasibility Report, 1994). Dissolution cavities of up to 3 meters wide are also likely to be encountered.
It is worth noting that dissolution and karstification in fractured zones along major and minor faults is likely to be encountered during tunneling and this karstification has resulted in open and/or partially filled large cavities with red clay and clayey sand.
Contaminated groundwater might also be possibly encountered during tunneling knowing that the tunnel will pass underneath residential areas. Septic tanks are one of the possible sources of such contamination. The tunnel also passes few kilometers down gradient from the Naame Landfill and possible leaks from this landfill might be encountered during tunneling works.
The land use along the areas of the Awali project varies between the hills and the coastal planes. The expansion of the coastal communities and the extension of the urban area from Beirut southwards also affect the land use along the project areas.
Photographs in Appendix C have been provided to illustrate the nature of the landscape at the locations of the various project elements.
The site of the Joun flow regulation structure lies at the side of a relatively steep valley. The only access road that leads to the existing tunnel adit was done during former works for the already existing power station tunnel. This road passes through terraced fields (some of which are used) and rough ground. An old spoil heap also exists in the site below the adit from the previous works.
The Wadi Abou Yabes Washout site lies in an isolated hillside location. Large aggregates works with associated polluting emissions are taking place at its lower end.
The proposed site for the Ouardaniye water treatment works lies in an open hillside location, gently sloping to the west. It is formed of rough, stony ground with a small Wadi along the northern side.
There is no major residential activity in the site area but greenhouses are very common in and around the site.
One frame for a house has been constructed at the site since this was first suggested as the site for the water treatment works. The access road to the site will follow existing roads. The Wadi discharges into Ouardaniye bay on the Mediterranean coast. This bay has a wide sandy beach, with rocky headlands to the north and south and it is popular for recreational activities, including bathing, with associated facilities being provided.
The inverted Siphon at Damour will pass under a deep, narrow valley. The Damour washout site lies in a very beautiful area in the valley, just next to the river where two restaurants and a picnic space are situated. Access roads to the shafts will cross virgin wooded hillsides.
The Khalde surge shaft and outlet portal sites also consist of open rocky hillside sites having a steep slope to the west. They lie adjacent to the new, high quality residential properties of some two to four stories.
The pipeline route from the outlet portal starts with a regraded, existing road, and continues along the side of the new coastal highway.
The Khalde flow distribution chamber will be constructed on a derelict site between the new highway and the old coastal road. Offshore, the coastal beach is used for some recreational activities.
The pipelines from the Khalde flow measurement, distribution and connection chambers to the proposed Hadath and Hazmieh reservoirs will pass from the old coast road to the main Chouwaifat road uphill to the reservoirs. The first 2 Km of this path consist of a busy, dual carriage way. The remaining part of the path consists of a standard width road. This path is surrounded by residential and industrial properties along its sides for most of its length.
The proposed Hadath 125 reservoir site consists of a terraced sloping valley, bordered by new apartment blocks to the north, a military barracks to the south, and a church and cemetery to the west.
The proposed Hadath 90 reservoir site lies on waste ground to the west of the military barrack and to the east of a tobacco manufacturing facility (REGI).
Further north the pipeline would pass through increasingly high class apartment residential blocks, generally along dual carriageways width roads.