с тем, чтобы не отвлекать силы и средства на привлечение техники и людских ресурсов HR

[Alex16]

В свое время было решено, что строительство руслоотвода будет осуществляться сторонней строительной организацией на основе отдельного контракта, с тем, чтобы не отвлекать силы и средства на привлечение техники и людских ресурсов и не строить канал своими силами.

It was once decided that the construction of the riverbed diversion canal would be carried out by an external construction company on the basis of a separate contract in order not to divert our resources for procurement of equipment and human resources and to avoid building the canal using our own resources.

in order to spare our efforts on procurement of equipment and human resources?

[loner]

consider:
It was then decided that a third-party company would be contracted to construct the riverbed diversion canal under a separate contract in order to avoid involvement of own equipment and human labor/workforce in procuring equipment/hiring personnel and building the canal.

[Shumov]

imho: It was once decided that (in order) to save costs and effort of providing machinery and manpower the construction of riverbed diversion canal would be contracted out .

если только вам платят не за кол-во знаков нв выходе))

[Alex16]

Спасибо! За кол-во знаков не платят...