Reference no: EM13240943

A contractor is responsible for drainage network cleaning and shall ensure that the required level of service is achieved. The required level of service is that any point in time no more than 3% of Drainage Inlet pits and no more than 3% of Drains are to be obstructed.

When a drain or drainage inlet pit is inspected the following assessment ratings are to be used:- 

0% reduction in hydraulic capacity = assessment rating 5,

5% reduction in hydraulic capacity = assessment rating 4,

10% reduction in hydraulic capacity = assessment rating 3,

20% reduction in hydraulic capacity (obstructed) = assessment rating 2,

significantly worse than 20% reduction in hydraulic capacity = assessment rating 1.

a) Produce an assessment of the service level for the quarter expressed as percentage of drainage inlet pits and drains that are obsrtucted over the drainage network

b)provide a full acount on the methodology used to arrive at the assessed service level. This shall include details on the level of confidence in respect of the assessment.

The following inspections recorded for the quarter are tabulated below

Rating 5 4 3 3 2 2 1 1 1 1 1 1 1

Percentage Full 0 1-5 6-10 11-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 100

No. of Pits 3192 16 9 11 13 8 9 25 51 65 56 18 24

The total number of inspections for the quarter was 3497.