Organizational and Technological Justification for the Use of a Mobile Dismountable Hydraulic Drilling Rig for Water Well Construction under Restricted Access Conditions

Drilling operations in developed residential areas are constrained by narrow access routes, fences, pavements, and landscaping elements. The aim of this study is to develop and substantiate an organizational and technological approach to the use of a mobile dismountable hydraulic drilling rig for water well construction under restricted access conditions. The study is based on a private residential site where the minimum passage width between the building and the fence was 1.1–1.2 m. Bringing a conventional heavy drilling unit directly to the drilling point would have required dismantling the fence and part of the landscaping followed by restoration works. The methods included engineering site inspection, dimensional analysis of equipment, decomposition of technological operations, comparison of two work organization alternatives, and normalized cost assessment. The investigated rig has a height of 2320 mm, a load-bearing structure width of 300 mm, a drilling table size of 300 × 310 mm, a disassembled set mass of approximately 250 kg, and an assembled operating mass of approximately 350–400 kg. A technological accessibility coefficient is proposed to relate the minimum passage width to the critical transverse dimension of a transported module. For a 630 mm module, the coefficient equals 1.75 for a 1100 mm passage and 1.90 for a 1200 mm passage, with geometric clearances of 470 and 570 mm, respectively. An organizational and technological algorithm is developed covering site inspection, route verification, module transportation, assembly, drilling, disassembly, and performance assessment. Eliminating temporary access preparation removes a group of costs estimated at 35–40% of the base project cost. The economic result is therefore interpreted as a consequence of the engineering and technological decision.