Je comprends 'L'écart en hauteur de l'embout d'aspiration de la pompe est/peut être réglé par le moyen d'un raccordement de chantier/raccordement effectué sur place.
Davantage de contexte permettrait peut-être d'affiner la traduction.

"Corrosion resistant, custom-designed fibreglass PUMP STATIONS
All joints are factory sealed by the butt and strap method. There ARE NO SITE JOINTS TO BE DONE, there is no haunching to be done. IF there is a pipe misalignment and A SITE JOINT IS NEEDED, then the joint can be made very secure with a fibreglass bandage.
https://www.armatec.co.nz/pump-stations"

" It has long been recognised that the achilles heel of a thermoplastics pipe system 1s the quality of the SITE JOINTING procedure. Successful site welding, and indeed the making of mechanical joints, requires a higher level of competence than the more conventional jointing methods associated with traditional materials"
https://www.pe100plus.com/PPCA/Site-Jointing-p959.html

"connection, site - joint m de chantier"
https://ia803408.us.archive.org/0/items/ossatures-metallique... [Dict. Montagu]

"Les unités de puits sans fosse [...]
• auront un RACCORDEMENT DE CHANTIER à joint fileté, à collerette ou mécanique vers la décharge latérale de l'unité sans fosse"
https://www.sac-isc.gc.ca/fra/1100100034922/1533666798632
"Pitless units shall:
• Have FIELD CONNECTION to the lateral discharge from the pitless unit of threaded, flanged or mechanical joint connection;"
https://www.sac-isc.gc.ca/eng/1100100034922/1533666798632