Oil Trenches a Continuing Threat to the Terrestrial Environment of Kuwait

By

Dr. Raafat Misak Ph.D.
Research Scientist, Remote Sensing/Environment and Earth Sciences
Kuwait Institute for Scientific Research,
Safat, Kuwait. (Email: rmisk@safat.kisr.edu.kw)

Dr. Samira A.S. Omar Ph.D.
Research Scientist, Aridland Agriculture Department/Food Resources
Kuwait Institute for Scientific Research,
Safat, Kuwait (Email: somar@safat.kisr.edu.kw) 

Dr. Shabbir A. Shahid Ph.D.
Associate Research Scientist, Aridland Agriculture Department/Food Resources
Kuwait Institute for Scientific Research,
Safat, Kuwait (Email: sshahid@safat.kisr.edu.kw)

Abstract

During the Iraqi occupation of Kuwait (August 1990 – February 1991), the Iraqi troops dug huge number of trenches at the southern portion of Kuwait, 10-15 km to the north of Kuwait – Saudi Arabia border and at Ras As Sabiyah area (northeastern part of Kuwait).  These trenches were filled with oil through pipelines from several oil fields in Kuwait.  The strategy of the Iraqi troops was based on setting the oil on fire to impede any land or sea attack by the coalation forces.  During the military operations of the liberation of Kuwait, the Iraqi troops had no chance to fire the oil.  During the rehabilitation phase followed Kuwait liberation, crude oil from some oil trenches was drained and transported to an oil lake at Burqan oil field.  Later on the majority of trenches were refilled with the exception of very few ones in the extreme southern coastal area.  After ten years of Kuwait’s liberation, heavy oil contamination of soils and vegetation is still observed in the strip extending between the Arabian Gulf on the east to wadi Al-Batin on the west and at Ras As Sabiyah area.  The amount of oil filled into oil trenches in this strip is estimated as 3.5x10⁶ barrels, and 2,213,366 m² soil surface was damaged.  The laboratory investigation (EC, pH, total petroleum hydrocarbons, heavy metals such as Ni, V and Pb) of the soil samples reveals that the soil is contaminated with oil to varying degrees of extent.  It ranges from clean soil (no oil pollution) to slight, moderate and highly contaminated with oil sludge.  The TPH ranges between 0.02% (clear soil) to 14.43% (sludge).  The heavy metals range between 3-14 mg kg^-1 (Ni), 8-32 mg kg^-1 (V) and 0.02-3.5 mg kg ^–1 (Pb).  It reflects that there is a continuing threat to human health and the natural resources of Kuwait. The oil remaining in the trenches will continue to mobilize through soil layers causing further pollution and deterioration of the shallow water table.  The study has the following main objectives; 1) to assess the magnitude of damage caused by oil trenches to the soils, vegetation and ground water; 2) to propose the cost effective action plan for soil rehabilitation (pilot study).

Methodology

• Identification of the geographic extent of oil trenches using the 1991-1992 aerial photos (scale 1:29,000).

• Determination of the specifications of oil trenches (length, width and depth) through field survey.

• Calculation of the amount of soils excavated during the digging of the trenches (total length x average width x average depth of trenches).

• Estimation of the amount of spilled oil into the trenches (total length of trenches x width x depth of oil in the trenches).

• Determination of the depth of oil penetration into the soil through exploratory drilling (large diameter boreholes).

• Identification of the various degrees of oil contamination of soils by depth.

• Sampling of contaminated soils at different intervals (from 0 to about 250 cm).

• Laboratory analyses for collected contaminated soil samples (EC, pH, TPH and heavy metals).

• Assessment of environmental damage to soils and natural vegetation on both sides of oil trenches along 100 m long transect, perpendicular on the trench.

About the Study

Duration:          8 years (1992-2000)

Phase 1:          1992 – 1994

Preliminary investigations (filed reconnaissance and visual remote sensing observations).

Output :           General damage assessment

Phase 2:           1995 – 1998

Detailed field survey and aerial-photo interpretation (photos of 1991-1992, scale 1:29,000).

• Recent maps showing the geographic extent of oil trenches

• Semi-detailed damage assessment (surface)

Phase 3:           1998 – 2000

Exploratory Drilling & Laboratory Analyses, ecological investigations.

Output:             Detailed damage assessment (surface and subsurface)

Background

• Oil trenches are oil filled ditches prepared by Iraqi troops on the ground surface at the southern border zone (Kuwait-Saudi Arabia) and the northeastern coast (Khor Al Sabiyah).

• Main component of strategic defense belt to impede the liberation of Kuwait by coalition forces through high fire wall (firing the oil trenches).

Along the southern border zone:

Trenches total length:           120 km

Amount of oil:           3.5 million barrel

Average dimensions of an oil trench:

Length              700 – 1100 m

Width               2 – 2.5 m

Depth               1.5 – 1.7 m

Mechanisms of Crude Oil Transit

To transit the crude oil from its supply area (Kuwaiti oil fields), a transit system was established by Iraqis.  The system consisted on the following:

• 42” (inch) diameter Main line

Length  :           97 km

Extension:         Managish oil field (east) to wadi Al Batin (west)

• Nine branches 10” (inch) diameter connected with the main 42” line

Length: 5 – 8 km

Extension:         Almost north-south

• Net of ten to thirteen 6” (inch) diameter sub-branches connected with each of the nine 10” (inch) branches.

Geographic Extent of Oil Trenches

Southern border zone (Arabian Gulf - wadi Al Batin)

1. Eastern Sector (Nuwassib – Wafrah)

2. Central Sector (Wafrah – Managish)

3. Western Sector (Managish – wadi Al Batin)

Inventory and Assessment of Environmental Damages

(southern border zone, a case study)

Environmental damages caused by oil trenches are differentiated into physical and oil related damages.  Physical damages are caused by the disruption of the desert surface with its vegetation cover and wild life habitats as a result of the mechanical activities performed during the construction of the oil trenches.  While oil related damages, i.e., pollution of soils, vegetation, wildlife and ground water are resulted from spilling of huge amounts of oil into the trenches.

Chronologically, the environment damages are classified as follows:

• Damages caused by the construction of oil transit system.

• Damages caused by the digging and oil filling of trenches.

• Damages caused by refilling and leveling of oil trenches.

Damages Caused by the Construction of the Oil Transit System

To fill the oil trenches with crude oil, a complex network of different diameter pipelines was established by Iraqis.  The network transported the oil from its main supply areas (Kuwaiti oil fields) to the trenches.  The oil transit system consists of a main line (97 km length, 42 inch diameter), nine branches (each is 5-8 km length, 10 inch diameter) and sub-branches (ten to thirteen 6 inch diameter). During the establishment of the oil transit system huge amounts of soils were excavated.  Moreover, wide surface areas with its vegetation and wild life species were severely damaged (Table 1).   As indicated from this table about 91350 m³ of soils were excavated (90% from petrogypsids and 10% from petrocalcids).  Regarding the surface of damaged area, it attains about 772.5 km² (90% in petrogypsids and 10% in petrocalcids).  The plant species which were growing on this area had severe mechanical and chemical (due to oil leakage) damages.  The damaged plant species are Stipagrostis plumosa, Haloxylon salicornicum, and Cyperus conglomeratus.

Table 1.  Damages to Different Types of Soils Caused by the Construction of the Oil Transit System

*  Based on calculation of length of main line (97 km) branches (63 km) and sub-branches (99 km), width of drilling (3 m for main line, 0.5 m for both branches and sub-branches and depth of drilling (3 m for main line, and 0.5 m for both branches and sub-branches).

Damages Caused by the Digging and Oil Filling of Trenches

The operations of digging and then oil filling of trenches caused severe damages to the environmental components.  About 1,844,202.5 m³ of soils were excavated.  The surface damaged area reaches 1,562,898 m².  The amount of oil spilled in the trenches attained about 396,498 m³ (Table 2).  The oil caused the death of wild life and damage to vegetation cover.  The most damaged plant species are the Stipagrostis plumosa, Haloxylon salicornicum, Cyperus conglomeratus and Halophytes. Heavy soil contamination till two meter depth is observed along the whole length of oil trenches.  Moreover, the shallow groundwater of the coastal sabkhas (Aquisalids) is highly contaminated by petroleum hydrocarbons.

Table 2.  Damages to Different Types of Soils Caused by Digging and Oil Filling of Trenches

Damages Caused by Refilling and Leveling of Oil Trenches

During the rehabilitation phase, the Ministry of Defence of Kuwait refilled the oil trenches using earthen materials.  To refill the trenches, additional amounts of soils were used (as the originally excavated soils were not enough).  Moreover, refilling operations were performed by heavy equipment, which caused additional damages to soils, vegetation and wild life habitats.  During the refilling of some trenches the oil flowed on the surface covering wide areas on both sides of the trench.  It is believed that the refilling and leveling of the trenches had increased the surface of the already damaged area by at least 20%.

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