Coll 5/85 ‘Airfield at Dharan for U.S.A.A.F.: Proposal to construct new airport at Bahrain (Hamala)’ [‎33v] (67/522)

APPENDIX A
DC 88050/1
1 A
BASRAH
1 .
General
The existing airfield is surrounded by water or main railway sidings, so
that extension of the runways is virtually impossible; only one runway,
bearing 118° - 298 ° has sufficient length for the operation of even medium
weight aircraft. This report is accordingly confined to this runway, and
the hard standings.
2, Subsoil
The subsoil is a fine silt, similar to that obtaining throughout the
Tigris-Euphrates valley, but apparently less stable, due to higher moisture
content than that at Baghdad; the salt content appeared to be fairly high*
Subsoil water level is about 3 ft. below ground level.
3• Drainage
A little airfield drainage has been undertaken to date (see Plan 2)
but drainage is not provided to runway margins. A scheme is now in hand
to provide powerful pumps at two points on the airfield to either pump out of,
or into the drainage canals on the west, south and east sides of the airfield
depending on the level of water in the Euphrates and Shatt A1 Arab. By
judicious use of these pumps it is hoped to maintain a reasonably constant
water table level under the airfield, and therefore practically constant
subsoil conditions.
A* Main Runv/a y and St andings
(See Plan 2 for diagram representation of areas of different construction.)
The main runway is, from an engineering standpoint, in two parts, the
southern 1000 metres, built in 1936 , being of lighter construction than the
northern 1000 metres built in 1 9A4*
The southern portion has, in general, a construction of A" consolidated
sand bitumen mix direct on the silt (in seme spots on clay filling) with a
75 - u running surface of gravel bitumen mix. This construction has failed under
present traffic, and is now receiving constant and heavy maintenance; it will
be reconstructed during the summer of 19 A 7 to a strength equal to that of the
remaining portion of the runway.
The northern portion has 1A" stone pitching under a carpet of either
3 " sand bitumen mix, or 2 " gravel bitumen mix - about 500 metres of each, the
gravel being at the nothem end, topped with a 1 if gravel running carpet.
The stone is rather soft limestone, and may be expected to "weather" rather
badly in the damp conditions on this airfield, while the top carpet has been
applied with an inadequate tack coat; as a result it has disintegrated over
major portions of its area, resulting in a loose pebbly surface, and one in
urgent need of resealing.
The main standing consisted originally of A" broken brick carpeted with
-p-" gravel macadam mix and has recently been covered by 6" - 9" stone pitching,
(random pitching) with a 1 " gravel macadam running carpet.
It is estimated that the bearing capacity of the standings and of the
northern 1000 metres of the runway is such that a 60,000 lbs. aircraft on
2 wheels may safely use them - it is not possible to give even a nominal bearing
value for the southern half of the runway, as this is rapidly dis-integrating;
with constant watching and day and night repair facilities available, it should
be possible to operate aircraft from it, but arrangements must be instantly
available to divert aircraft in case of unusual rainfall, or an increase in the
rate of failure.