ATTACHMENT-2

BOREHOLE AND WATER SUPPLY ACCESSORIES ADDITIONAL CLARIFICATIONS

1. SECONDARY BOREHOLE

Due to the scale of the new extension it has been assumed that a new water supply system will be developed, making use of the bore hole well mentioned in the report “Specifications for Modjo Dry Port Bore Hole Drilling at Modjo” prepared by the “Water Work Business Unit” and dated 2002. This borehole is located at the north east of the development area as indicated in Figure 1.1 below.

Currently there exists no pumping system in place for this well however based on information provided from ESLSE, the depth of well is 160m and the output flow is 6 l/s. It should be noted though that these values have only been provided verbally, as no documentation exists to verify such values.

Figure 1.1: Location of new water supply well

Figure 1.2: Secondary bore hole well

2. Domestic Water supply facilities clarifications

Figure 2.1: Water reservoirs and technical utilities

Figure 2.2: Section utilities arrangement

Shut-off gate valves shall be installed in front of every facility / building where potable water connections are required. Furthermore, the shut-off gate valves shall be placed at each pipe work crossing in order to separate pipe lines for possible inspection and repair without not having to shut off the whole potable water system, see Figure 2.3.

Figure 2.3: Potable water network connection

Air release valves shall be installed at the main high points of pipe work at each level. Air release valves are required to evacuate air from the main high points in the line when it is filled with water, and to allow the discharge of air accumulated under pressure.

In order to isolate and empty specific sections of the potable water network several emptying openings are foreseen. The emptying openings consist of a pipe which is connected to the potable water network by a valve and drains into a manhole. The potable water will be discharged from the manhole through an overflow into the storm water network.

The system shall be designed to prevent dead ends as far as possible. If for any reasons dead ends cannot be prevent a flush and cleaning facility shall be arranged to flush the pipelines in regular time intervals. Additionally, the largest consumer shall be located at the end of the line to guarantee constant circulation of water. The minimum pressure head for the potable water network shall be 1.5 bar at the farthest sampling point.

The water quality shall meet all Ethiopian requirements for potable water. Drinking water is defined by distinct quality requirements stated in various international drinking water quality standards such as Water Framework Directive (European Union), U.S. Environmental Protection Agency (EPA) standards (USA) as well as guidelines published by the World Health Organization (WHO). Those standards and regulations define limit values of chemical, physical and microbiological water ingredients and should be followed.