Title of the task: Inspection of Wastewater reclamation facility
DETERMINING PIPE LEVELS
When you need to check for vertical levels, i.e., vertical drainage pipes, the back edge of the spirit level is placed against a straightedge, which is then positioned against the vertical plane to be checked. If the bubble is between the graduations, the plane is level. Where the bubble lies outside the graduations, the pipe is moved the straightedge until the bubble is centrally placed. This will allow you to determine any unevenness on the vertical plane. During the inspection, the sloping pipes were marked with x for rectification.
To use a spirit level properly, the level should be positioned in the Centre, on a firm horizontal or vertical surface. If the plane to be checked is not even, place a straightedge on top and the spirit level on top of the straightedge. Spirit level in the bubble should sit between the graduation marks. Where the bubble sits over or out of the graduation marks, adjust the left or right side. When the left side is too high, the bubble will sit on the right side of the graduation marks and vice-versa for the opposite side.
Fig 1. spirit level sitting outside graduated marks
Fig 2. Spirit level inside graduation marks after rectification
Scale and area measurements
The scale is the ratio of a distance on an aerial photograph to that same distance on the ground in the real world. It can be expressed in unit equivalents like 1 inch = 1,000 feet (or 12,000 inches) or as a dimensionless representative fraction (1/12,000) or as a dimensionless ratio (1:12,000).
The ground distance can be measured with surveying equipment, it may be known in advance, it can be calculated by multiplying the measured distance on a map by the map scale, or it can be approximated using the map’s scale bar. If the path or road you wish to measure curves, you can use a piece of string or a ruler to measure the length, lay the piece of string on the road segment, and then straighten it out and measure how long it is. During the inspection, no scale issues were found. All the scales were checked and confirmed to be in line with the ground measurements.
Fig 3. Measuring ground distance
Fig 4. Matching ground and map distance
Slope
The slope is a measure of the change in elevation. One way to express slope is as a percentage. To calculate the percent slope, divide the difference between the elevations of two points by the distance between them, then multiply the quotient by 100. The difference in elevation between points is called the rise. The distance between the points is called the run. Thus, percent slope equals (rise / run) x 100.
The tolerance for the inclination of the PVC drainage pipes was 5%. Beyond that, the pipes needed to be rectified by reducing the inclination. The pipes with slope tolerance of more than 5% were marked x for rectification. The bindings were loosened, and the horizontal position changed by reducing the slope.
Fig 4. Calculating slope percentages
Fig 5. Taking measurements for slope calculations
Anomalies and rectifications
During slabbing of the floor, some pipes were displaced by the vibration movement of the mixer, the force of the concrete, the vibrations of the generator during casting. Some steel binders were also interfering with the pipe alignment in the course of their work, i.e., by leaning on the pipes or tightening their steel closely to the pipes. In the process, they lost their vertical inclination (900 ).To avoid such displacement cases from happening in the future, we ensured that the pipes are tightened using binders and also ensured that a qualified Quality assurance officer from the MEP department is always present in the field to ensure rectification of the displaced pipes before the concrete dries up. In the case of the displaced pipes, the contactors of Jawab tech agreed to cut them horizontally in the ground level replace them with vertically inclined pipes. This is possible because the displacement of 1 to 2 cm is allowed.
Fig 7. Previous tightening
Fig 8. Firmly tightened pipes
Recommendations
A quality assurance officer should be present in the filed during the installation of the drainage pipes and also during slabbing to ensure proper installation and, at the same time, avoid displacement of the properly installed pipes. Plumbers from Jawab tech should have the right working equipment, i.e., levels, to ensure the vertical installation of pipes. The pipes should be properly tightened using binders at the ground level to avoid displacements.
Fig 9.Allignment after inspection and rectification