A. 1) The Plaintiffs are co-contractors for the construction of each of the wastewater treatment facilities (hereinafter “the instant construction facilities”) among the above construction works (hereinafter “the instant construction facilities”) that were subcontracted to the Defendant, as co-contractors for the Gwangju-ju (Yedong 2), the Seoul-ju (K) Highway 5 (Game Games), and for each of the instant construction works (hereinafter “the instant construction facilities”). The Defendant is a subcontractor who subcontracted the instant construction works from the Plaintiffs.

B. (1) On June 18, 2015, the Plaintiffs entered into a subcontract with the Defendant for construction period as to the instant construction work from June 19, 2015 to November 10, 2016, with the construction cost of KRW 1,244,100,00 (including value-added tax). (2) At the time of construction estimates sent by the Defendant to Plaintiff HoS Construction, the terms “processing capacity: 250 tons/day, 1 place, and 1stm”: (1) BODS: 5 pm: 20 pm; (3) T-P: 1 pm” (hereinafter “the instant outline clause”).

3) After November 9, 2016, the Plaintiffs entered into a modified contract (hereinafter “instant subcontract”). The Defendant completed the instant construction after completion of the construction, and received notification from the head of Bupyeong-gu Gun that the instant wastewater treatment facilities were properly installed on October 14, 2016 after filing an application for a completion inspection pursuant to Article 37(1) of the Sewerage Act. D. Imposition of administrative fines and facility improvement order 1) on February 1, 2017 during the Defendant’s trial operation period, and as a result of the water quality inspection, it was found that the water quality of the instant wastewater treatment facilities exceeds the standards for the water quality of the private sewage treatment facilities (BOD, TN-N-N, and the total water ledger) publicly notified at the time of the water quality inspection.

2. The two-dimensional group is the ordering person.