"Borehole survey
A borehole survey was carried out across the site to examine the nature of the below-ground deposits. Cores were retrieved from the ground in plastic sleeves and cut open to look at the soil stratigraphy.
The survey followed the line of the Birmingham & Worcester Canal and showed that the depth of the natural deposits ranged from a depth of 1.30 metres (14.8 metres OD) in the north of the site (Borehole BH 4) to 4 metres (8.66 metres OD) in the south (Borehole BH 6). "
http://www.archenfield.com/Worcester RWP Portland Walk.htm

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Note added at 29 mins (2010-09-16 11:57:52 GMT)
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Methane studies for the Channel Tunnel ...
by CD Warren - 1991 - Cited by 2 - Related articles
1 Jun 2010 ... level of -150 metres OD. Drill-hole sections of the ..... (metres betow NGF). v v. Zone of Disturbance. Limestone Plateau ...
qjegh.lyellcollection.org/cgi/reprint/24/3/291.pdf

"Results of topographical survey showing Mound 1 and Mound 2, adjacent to Collierstown 1. ... The colours shown on the survey results are indicative of metres O.D. (Ordnance Datum), which are referenced in the column on the right hand side of the image."
http://www.m3motorway.ie/Archaeology/Section2/Collierstown1/

"These are referred to as flood cells and they indicate areas where the ground is less than a level of +4.5 metres relative to Ordnance Datum (OD)."
http://www.environment-agency.gov.uk/static/documents/Resear...

"These are referred to as flood cells and they indicate areas where the ground is less than a level of +4.5 metres relative to Ordnance Datum (OD)."
http://www.environment-agency.gov.uk/static/documents/Resear...

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Note added at 36 mins (2010-09-16 12:04:22 GMT)
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However also see previous Kudoz question where the merits of translating NGF are debated ...
http://www.proz.com/kudoz/french_to_english/ships_sailing_ma...–_x_inférieure_et_000_m_supérieure.html

The NGF is related to some water level in the Mediterranean, so "above sea level" is what it ultimately means.

Le nivellement général de la France (NGF) constitue un réseau de repères altimétriques disséminés sur le territoire français métropolitain continental, ainsi qu'en Corse, dont l'IGN a aujourd'hui la charge. Ce réseau est actuellement le réseau de nivellement officiel en France métropolitaine.
On distingue cependant deux réseaux :
• NGF - IGN69 pour la France métropolitaine, le « niveau zéro » étant déterminé par le marégraphe de Marseille ;
• NGF - IGN78 pour la Corse, le « niveau zéro » étant déterminé par le marégraphe d'Ajaccio.
[ ... ]
Le réseau IGN 1969 : établi de 1962 à 1969 par l'Institut géographique national. On a conservé comme point de départ le « zéro normal » défini par Lallemand. Le zéro de nivellement est à 1,661 m sous le repère fondamental situé dans le local du marégraphe de Marseille. Ce réseau est régulièrement recalculé (calcul de compensation). Ainsi, les cotes des repères de l'IGN 69 par rapport au « zéro normal » peuvent avoir été modifiées depuis la première détermination de l'altitude des repères en 1969.
http://fr.wikipedia.org/wiki/Nivellement_général_de_la_Franc...

NGF: Niveau général français ou nivellement général de la France, c'est l'altimétrie d'un point mesuré par rapport à un 0 théorique qui est grosso modo le niveau moyen de la mer ( à Marseilles). Et d'ailleurs ça colle complètement la différence d'altitude sur dalle et sous dalle donne 24 cm. Voilà les plans structure n'ont quasiment plus aucun secret pour toi. Seulement les NGF sont donnés en mètres, et les épaisseurs sont données en centimètre, ce qui explique que tu n'y arrivais pas (tu dois être physicien pour être si rigoureux au niveau des unités)
François
http://www.cadxp.com/XForum print-fid-125-tid-18069.html


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Note added at 3 hrs (2010-09-16 14:41:33 GMT)
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Or "masl".

The elevation or altitude in Meters above sea level of any location, object, ... Meters ABOVE SEA LEVEL IS SOMETIMES ABBREVIATED as m.a.s.l. or m.s.l. ...
en.wikipedia.org/wiki/Meters_above_sea_level

Foundation slab. 18752 sq m of 900mm thick pressure slab ... ABOVE SEA LEVEL, with a floor area of 494.3 sq m (5320 sq ft). Concrete ...
www.trac.sun.ac.za/images/.../PETRONAS Twin Towers.pdf

For example, if the location of your house is 100 FEET ABOVE SEA LEVEL, ... least 100 inches (8 feet plus 4 inches for the foundation slab). ...
www.chiefarchitect.com/support/displayfaq.php?faqNumber...

Building 100, the Rocket Engine Test Facility operations building, is on a flat, featureless area at an elevation of 761' ABOVE SEA LEVEL. It stands close to the eastern edge of a steep ravine throughwhich Abram Creek flows. Access to the site is through a driveway off Walcott Road in the NASA-Glenn complex at Lewis Field.
http://www.grc.nasa.gov/WWW/retf/textFiles/HAERpdfs/Bldg100R...

Another option, once you've established the units involved, is "El." which stands for "elevation above sea level" or "elevation above whatever datum is valid for the project", or you can specify the units : "El. 239" or "El. 239m".

Lateral view of the male genitalia of Oeneis bore - BC, McBride Peak, EL. 2460 M, 29 July 1985, J. and S. Shepard Figure 56. Left valve of Erynnis species: ...
books.google.com/books?isbn=0774808098...

wells penetrate the Ector Chalk Formation at a depth of 3000 feet (EL. -2460 FT.). Both the Campbell nd Sulphur Bluff fields are located within the ...
doi.aapg.org/data/bulletns/1965-67/data/pg/0050/.../1510.htm

regions between EL.1245 M∼1460 m. Figure 5 shows ... The data obtained from the monitoring equipment at the elevation of 1250 m. Figure 8. ...
www.crcnetbase.com/doi/abs/10.1201/9780203885284-c258