It is a complicated underground drilling project. Part section consists of red hard sandy rock around 30mpa of hardness strength, another section consists of pebble rock with proportion of 50~60%, diameter 100~150mm,thickness around 1~1.5m. Customer need to lay a diameter 220mm steel pipe of 190m into it. Based on photos and soil survey report customer provided, ZLCONN suggest the suitable 40T ZL400A HDD Machine, rock drilling bits, drilling methods and suggested bentonite to customer. And send a experienced machine operator onsite for assistance. Finally customer succeeded with the job with another 3cbm mud pump, 152mm rock drilling bits, F300, F400 rock reamers, also around 18t bentonite.And after 4days hard work, we successfully drilling to the target pit and avoid the pebble layer successfully. This project is another classic example that ZLCONN not only knows the machine but also the construction, that’s why HUNAN ZLCONN HDD machine is always loved by customers.