Eastern Harbour Research Articles

Risk management of SSDS stage I Tunnel B – tunnelling under the eastern harbour crossing tunnel in Hong Kong

Tunnel B of the Stage I Strategic Sewage Disposal Scheme (SSDS) has an excavated diameter of 3.2 m and it was excavated with a hard rock tunnel boring machine 75 m below the Eastern Harbour Crossing Tunnel (EHC) in the Victoria Harbour of Hong Kong. The EHC is an immersed tube structure built in 1990 and the structure was made up of fifteen rectangular reinforced concrete box segments, each of about 125 m long, connected together by flexible joints that are under compression at working condition. The major risk that had been identified was that if any ground movement in the EHC tunnel boxes had occurred, as a result of groundwater drawdown due to large inflow into Tunnel B, the flexible joints connecting the two adjacent boxes of the structure could have lost its effectiveness in water-sealing, with the consequence of seawater entering the boxes under full hydrostatic pressure. The EHC is a major trunk road in Hong Kong and should water seeps into the structure, traffic would have been devastated resulting in huge financial loss to the city. To identify and to manage the risk of potential movement when Tunnel B was approaching under the EHC, site specific ground investigation comprising of a 800 m long horizontal exploratory drill hole and geophysical survey had been carried out to identify the geological condition and groundwater regime ahead of the tunnel. The geophysical survey was specifically carried out to investigate any accretion of silt above the EHC box segments in order to properly model the correct boundary condition in a seepage analysis. Sensitivity analysis on the effect of different boundary conditions to settlement prediction using a full range of soil parameters has been considered. It is found from this study that the presence of a blanket of marine deposit (above the tunnel box segment) is an important factor that could increase the settlement prediction by many orders of magnitude as compared to the case without marine deposit. The marine deposit is a very low permeability material, which could act as a cap and retard or prevent the downward flow of theseawater from recharging into the system. The best estimate of ground settlement likely anticipated due to tunnelling was arrived, based on engineering judgment and experience consistent with other project studies. When Tunnel B was 600 m away from the EHC, additional probing and shortening of cuts were exercised; settlement and joint opening were continuously monitored on a bi-daily basis; and inflow into Tunnel B was measured daily. All of these measures were carried out in accordance with the risk management plan. Three different levels of warning systems (Alert, Action and Alarm) are described in this paper. (A) This paper was presented at Safety in the underground space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and the 32nd ITA General Assembly, Seoul, Korea, 22-27 April 2006. For the covering abstract see ITRD E129148. Reprinted with permission from Elsevier.

Holocene Depositional Patterns and Evolution in Alexandria's Eastern Harbor, Egypt

Abstract This investigation focuses on sedimentological attributes and the litho- and chronostratigraphic framework of Holocene sediment core sections recovered in Alexandria's Eastern Harbor in Egypt, for many centuries the major port in the southeast Mediterranean. Holocene sediment trapped in the harbor, formed of marine calcareous sand, muddy sand, and mud, are examined to define major depositional patterns that developed before and after expansion of Alexandria in the 4th Century BC. Petrologic and radiocarbon data indicate that the harbor formed between two Pleistocene carbonate sandstone (kurkar) coastal ridges and was flooded by seawater during the transgression at about 8000 years before present (BP). Sediments accumulated at an average rate of 1–3 mm/y largely by wave- and wind-driven currents driving material from the Egyptian shelf into the high-energy basin. The association of distinct biological components, failed slump-like sediment strata, and important hiatuses (time gaps) record the epis...

Tributyltin pollution in sediments from Alexandria's coastal areas

Presence of Tributyltin (TBT) in Alexandria’s coastal water areas has been demonstrated by measuring concentrations of this compound. The TBT was measured in sediments from three docking areas namely: Western Harbour, Eastern Harbour and Abu Qir Bay. The sediment of those areas has been affected by marine traffic and other industrial activities. This is reflected by the distribution of TBT in the sediments nearby the shipyards in the three docking areas of the region where the average values of 258.6 ηg TBT/g for Western Harbour; 126.4 ηg TBT/g dw for Abu Qir Bay and 42.3 ηg TBT/g dw for the Eastern Harbour were recorded. This fact reflects the effect of industry and marine traffic on the marine environments of the Alexandria region.

Spectral study and antifouling assessment of some thiosemicarbazone derivatives

Three thiosemicarbazone derivatives were synthesised: p‐chlorobenzylideneamino thiosemicarbazone, p‐itrobenzylideneamino thiosemicarbazone and p‐N,N ′‐dimethylminobenzylideneamino thiosemicarbazone. The structures of these compounds were characterised by elemental analysis, IR, 1H NMR and UV spectral measurements. The antifouling properties of the compounds were evaluated through the incorporation of each compound in a marine coating system and testing the system in Alexandria Eastern Harbour water. The results are discussed in the light of the leaching rate of the compounds from their paint films, and their interaction with paint matrix.

Source diagnostic and weathering indicators of tar balls utilizing acyclic, polycyclic and S-heterocyclic components

This study represents a forensic chemical analysis to define the liability for the coastal bitumens polluting the beaches of the Mediterranean city of Alexandria. Six tar balls collected from several locations along the coast of the city were analyzed for their acyclic and polycyclic hydrocarbons as well as sulfur heterocycles using GC/FID, GC/AED and gas chromatography/mass spectrometry techniques. The analysis of one Egyptian crude oil is also included as a possible source oil. The tar ball samples were at early stages of weathering. Based on the GC traces and biomarker signatures, the tar balls could be genetically different. One sample collected from the Eastern Harbor region appears to be a Bunker C type fuel produced from Egyptian crudes. The refining process has removed the low molecular weight components. On the other hand, the wide n-alkane distribution together with the absence of an unresolved complex mixture suggests that crude oils probably from tank washings, ballast discharges or accident spills from tankers could have contributed significantly to the other tar ball samples. The distribution of source specific hopane and sterane markers revealed that the tar samples probably originate from different oil fields.

Contamination of polycyclic aromatic hydrocarbons (PAHs) in microlayer and subsurface waters along Alexandria coast, Egypt

The residues of seven polycyclic aromatic hydrocarbons (PAHs) pollutants in microlayer and subsurface seawater samples collected from Alexandria coast, Egypt, were analyzed by gas chromatography–electron-impact mass spectrometry-selected ion monitoring mode (GC–MS-SIM). The pollutants studied were, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene and benzo[ a]pyrene. Total PAH levels in microlayer ranged from 103 to 523 ng/l, while it ranged in subsurface samples from 13 to 120 ng/l. The Western Harbor location recorded the highest level of PAHs pollutant over all the other location for both subsurface and microlayer waters. The two major PAHs in microlayer water at the Western Harbor were fluorene and phenanthrene, making up 27% and 20% of the total PAHs, while the two major PAHs in subsurface water at the Eastern Harbor were phenanthrene and fluoranthene recording up 21% each of the total PAHs. The total PAH levels were generally in the nano-gram per liter for microlayer and subsurface seawater samples. The dominant PAHs in both subsurface and microlayer samples were fluoranthene, pyrene and benzo[ a]pyrene. The microlayer enrichment factor at Alexandria’s Mediterranean coast was ranged from 29 for fluorene to 3 for phenanthrene and benzo[ a]pyrene which showed PAHs concentration in the microlayer with an average of five times more than the total PAH in the subsurface samples.

Succession of heterotrophic and mixotrophic dinoflagellates as well as autotrophic microplankton in the harbour of Alexandria, Egypt

In the Eastern Harbour of Alexandria, three trophic categories of microplankton, heterotrophic dinoflagellates (HTD), mixotrophic dinoflagellates (MTD) and obligately autotrophic microplankton (OA) were studied in terms of species richness, numerical standing crop, biovolume and carbon biomass during the summer of 1999. Although represented by a small number of species, MTD proved to be the most important trophic category, contributing more than half the standing crop and the carbon biomass. Almost all blooms were dominated by the MTD species Prorocentrum minimum and Scrippsiella trochoidea. The HTD and the OA were richer in species but lower in biomass. Mixotrophic and autotrophic cells 50 µm.

The 3D physical-biological model study in the Egyptian Mediterranean coastal sea

The ecosystem of the Egyptian Mediterranean coastal area between longitudes 29°45′ E and 33°45′ E was seasonally investigated. The obtained data sets for a variety of environmental variables were previously interpolated over the studied area, and used in the coupled physical-biological model Fin-Est. Here, the model has been implemented to solve the central problems in case of modeling local areas and the handling of open boundaries and initial conditions, which almost have significant influence on the results, of both the hydrodynamic and the ecosystem models calculation. In the present study, a multi-step calculations procedure was used in applying the 3 D coupled model at first for the entire Egyptian Mediterranean coastal area. Then, it runs for local areas obtaining the initial conditions and the open boundary ones from larger area calculations. In particular, the zoom-in approach was used for the detailed study of the Eastern Harbour of Alexandria city-Egypt (model grid step = 50 m.) selected from the larger Alexandria Sea (model grid step = 1.25 Km), which in turn was chosen from the Egyptian Mediterranean coastal area (model grid step = 12.5 km). The sensitivity of the model simulations to both physical and biological main factors of the studied areas is tested. Both climatic conditions and land sources effects are considered among the model forcing factors. The resultant simulations are compared with the actual measured values of the parameters. The model sensitivity test results are discussed in the context of the model's capabilities and limitations, and with reference to the available knowledge of the ecosystems of the study areas.

Approaches to environmental restoration of a polluted harbour with submerged archaeology: the Alexandria case study

Many invaluable underwater buildings of archaeological interest in Alexandria were discovered in 1996 at different sites in the Eastern Harbour of Alexandria. There is a belief that the best way to protect these invaluable heritages is to transfer them to an underwater park or museum. Obviously, the execution of such a project depends essentially upon the water quality (including water transparency) improving in the future. The harbour is presently polluted by discharge of wastewater effluents from different sources. It has recently been decided to restore this important coastal area through: (1) stopping the direct discharge of wastewater effluents into this semi-enclosed harbour in 1993 and (2) gradually reducing the discharge of the municipal wastewater through marine outfalls at two sites lying at the outer sides of the harbour. Zero discharge is expected to be effective by the end of the year 2001. The present work, therefore, is a follow up of the study of water quality in the harbour after 1993: in 1996 and 1999–2000. The water quality of an open sea reference station was also studied for comparison. The results reveal occurrence of an improvement of the environmental conditions in the harbour. The water has turned from being eutrophic to mesotrophic. The harbour is expected to become meso/oligotrophic as soon as the complete cessation of the discharge from the two outside sources is attained.

Forecasting daily traffic volumes—the concept of capacity

An important factor in preparing forecasts of future traffic volumes for build–operate–transfer projects is the matter of the daily ‘capacity’ of the completed highway. This paper presents the results of detailed analyses of observed traffic patterns and estimation of the daily traffic ‘capacity’ of the Eastern Harbour Crossing and Cross-Harbour Tunnel in Hong Kong. The results indicate the importance of assessing the distribution of daily traffic throughout the day when preparing traffic and revenue forecasts for future projects of this type.

Marine anti‐corrosion paints based on thiouracil compounds

The inhibition of marine corrosion of steel by 6‐amino‐2‐thiouracil (I) and its derivatives 6‐benzylideneamino‐2‐thiouracil (II) and 6‐p‐chlorobenzylideneamino‐2‐thiouracil (III) has been tested on laboratory scale using electrochemical technique which was performed on mild steel in sea water medium and on field scale through the incorporation of the compounds individually in marine paints compositions. The paints containing the compounds were applied on unprimed steel and the coated panels were tested in Alexandria Eastern Harbour water (Egypt). The electrochemical measurements indicated that both compounds (I) and (III) acted as cathodic‐type inhibitors, but the data of compound (II) showed neither cathodic nor anodic inhibition. Two marine paint compositions were prepared using different binder materials. The three compounds were added individually in both paint compositions. The paint composition based on the soluble resin material as a sole binder and containing compound (I) showed the best corrosion protection of its steel surface till more than two months followed by the paint composition containing compound (III). The same paint containing the compounds showed antifouling property for four months.

Organochlorine Contaminants in Microlayer and Subsurface Water of Alexandria Coast, Egypt

Abstract The surface microlayer of seawater is a potential enrichment site for hydrophobic organic compounds. Concentrations of pesticidesand congeners of polychlorinated biphenyls (PCBs) in the microlayer and subsurface waters of Alexandria coast were assessed. A 0.22 m2 screen was used to collect microlayer samples at 12 stations in June 1997. The samples were analyzed by gas chromatography with electron capture detection (GCECD) and confirmed by GC with mass spectrometry. Ten organochlorine pesticides and 10 PCB congeners were measured. The surface microlayer was enriched 2- to 3-fold in pesticides and PCBs. The most contaminated locations studied were Abu-Quir Bay and the Eastern Harbor. This study provides the first record of residues of PCB congeners in the studied areasand the first data about microlayer enrichment at Alexandria's Mediterranean Coast.

The Relationship Between Iodine, Chlorinity, Ph, Reactive Phosphate, Nitrite and Organic Matter in the Coastal Water of Alexandria

Water samples were taken from 12 stations at El-Dikheila Harbour, El-Mex Bay, Western Harbour, Qayet Bey outfall, Eastern Harbour, El-Ibrahemiya, Gleem, Sidi Bishr and Mandara, during January, April, August and November 1995. the area lies between latitude 31˚ 8′ and 31˚ 17′ North and longitude 29˚ 47′ and 30˚ East. the annual mean of chlorinity (11.69-20.5%0), pH (7.9-8.3), reactive phosphate (0.31-2.24 μM), nitrite (0.18-1.98 μM), oxidizable organic matter (1.97-8.95 mgO2 1-1), iodide (21.14-46.74 μg 1-1) and iodate (4.61-2.04 μg 1-1) were measured. Iodide content in water is three times higher than iodate. Iodide is positively correlated with chlorinity (r=0.65) and iodate (r=0.45), while it is negatively correlated with nitrite (r= -0.72), oxidizable organic matter (r= -0.55) and pH (r= -0.4).

Water Discoloration in Alexandria, Egypt, April 1993. I. Occurrence of Prorocentrum Triestinum Schiffer (Red Tide) Bloom and Associated Physical and Chemical Conditions

Abstract A yellow-brown coloration of water developed in the Eastern Harbour of Alexandria (Egypt) during April 1993. the dinoflagellate Prorocentrum triestinum, the causative organism, culminated in a population peak of 71–106 cells 1−1, chlorophyll a nearly 361 μgl−1. the bloom occurred with a thermohaline stratified water column and low surface nutrient levels. Water temperature was considered a crucial environmental factor controlling the occurrence of P. triestinum and nitrate was significantly correlated with its counts. the high relative growth constant (3.4 d−1), calculated just prior to the massive occurrence of the species, explains the rapid development of the bloom. A comparison with the earlier phytoplankton studies in the harbour is made.

Listeriaspecies in some aquatic environments in Alexandria, Egypt

Listeria were detected in surface and bottom water, fresh fish and/or shellfish samples collected from the Eastern Harbour of Alexandria (EHA), Lake Mariut and fish farm areas. L. innocua was found in all studied areas, whereas L. monocytogenes was detected only in EHA and Lake Mariut. However L. welshimeri was recovered from only one site in Lake Mariut. In EHA, the incidence of Listeria spp. and L. monocytogenes in surface water (11 samples) were 81.8 and 36.3%, in bottom water (11 samples) were 45.5 and 18.2%, in fresh fish (14 samples) were 42.8 and 21.4% and in shellfish (4 samples) were 75 and 50%, respectively. In Lake Mariut, the same incidence were 58.3 and 25% in surface water (12 samples), 41.6 and 16.6% in bottom water (12 samples) and 45 and 27% in fresh fish (11 samples), respectively. In the fish farm Listeria spp. were detected in one of the two surface water samples while bottom water (2 samples) and fresh fish (2 samples) were free from Listeria spp. including L. monocytogenes. L. monocytogenes was prevalent in EHA and Lake Mariut environments where domestic sewage was being discharged, while it was absent in the fish farm with no sewage effect.

The Effect of Sewage Discharge On Water Quality Off the Coast of Alexandria in Spring and Summer

Abstract Water samples were taken from 7 transects at El-Anfushy, Eastern Harbour, El-Ebrahymea, Stanly, Gleem, Sidi-Bishr and El-Asafra along the coast off Alexandria. the area lies between latitude 31°10′ and 31°20′ N and longitude 29°55′ and 30° E. Nitrate, nitrite, ammonium, urea, dissolved inorganic phosphate, silicate and pH values were measured with average values 1,13, 0.43, 1.41, 1.21, 1.71, 7.16 μmol l−1, respectively. the investigated area is considered to be eutrophic. Levels of nutrients measured in 1991 are all significantly higher than those found in the same area in 1976.

Petroleum hydrocarbon fingerprinting and sediment transport assessed by molecular biomarker and multivariate statistical analyses in the Eastern Harbour of Alexandria, Egypt

The Eastern Harbour (EH) of Alexandria, a heavily polluted southeastern Mediterranean basin, is subjected to petroleum contamination from two different sources. Surficial bottom sediments sampled inside and outside the harbour were analysed for organic geochemical markers in order to assess and track the aliphatic hydrocarbon signature in the bottom sediments. The aliphatic hydrocarbon compositions were determined both quantitatively and qualitatively for the alkanes, UCM, and biomarkers, including acyclic isoprenoids, tri- and tetracyclic terpanes, hopanes, and steranes/diasteranes. The data indicated a petroleum product end member characteristic of the EH. In order to differentiate among the possible petroleum sources in the area, biodegradation indices derived from the biomarker data were calculated for two possible end member sources, namely untreated sewage and petrochemicals, then compared statistically and experimentally with the data for the surficial bottom sediments. As a result, high levels of sewage-derived petroleum hydrocarbons were dominant in the area rather than direct input from boating activities or urban run-off. A multivariate statistical approach, including both factor analysis and linear programming technique, was used to determine the end member compositions and evaluate sediment partitioning and transport in the EH area.

Ecological Study of Spring-Early Summer Phytoplankton Blooms in A Semi-Enclosed Estuary

Abstract A sampling station in the Eastern Harbour of Alexandria was operated for 51 days between 2 March and 12 June, 1991. the harbour had different wide physical and chemical variations. Six distinct phytoplankton blooms occurred during this period. It is concluded that the physicochemical conditions affected the phytoplankton community structure and species composition. A dense diatom bloom could be maintained in a very weak and/or stabilized water column. A diatom bloom does not necessarily accompany an enhanced nutrient period. the depletion of nutrients and establishment of thermal stratification probably created favourable conditions for dinoflagellate and flagellate species to achieve blooms. the species composition could be shifted over the short term and a dense phytoplankton bloom could possibly dissipate in a few days.

Sewage Disposal as a Source of Phosphorus in the Coastal Environment of Alexandria

A preliminary attempt was performed to assess the relative impact of sewage and waste water discharge on the different phosphorus forms and their contribution to the total phosphorus balance in one of the most polluted basins off Alexandria region, the Eastern Harbor, representing its coastal marine environment The annual input of DIP to the harbor basin during the period 1985-1986 from land run-off, precipitation and flux from sediment was 567 Kg, 6.5 Kg and 520 Kg, respectively. On the other hand, about 860 Kg of phosphorus are removed annually through phytoplankton assimilation. A considerable part of the phosphorus budget of the harbor basin, i.e 400 Kg/yr is compensated from the flux exchange with highly phosphorus-rich sewage water from Kayet Bay sewage outfall.

Incidence and ecology of marine fouling organisms in the Eastern Harbour of Alexandria, Egypt

The seasonal changes, intensity and constituents of fouling developed on exposed test panels for short and long term intervals are studied in relation to the prevailing environmental conditions in the Eastern Harbour of Alexandria, during March 1983 to March 1984. The intensity of fouling on exposed test panels for long durations is considerably more dense than the total fouling developed on exposed panels for short term successively during the same period. The fouling colonized on submerged panels for long intervals reach to a “saturation point” after 3 to 6 successive months.