Core Area

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Definition - What does Core Area mean?

The core area in the context of a sewer network is the sewer system's critical sections. These sections are more likely to experience severe hydraulic problems. The core area of a sewer system requires regular inspection and maintenance more than in areas that aren't critical to the system's operation. Although the critical area may include portions distributed over the whole system, it's treated as a single entity.

The core area of a sewer network is the system's critical sewer sections. These sections are more likely to experience severe hydraulic problems.

The core area of a sewer system requires more monitoring than areas that aren't critical to the system's operation - those that could cause systemwide disruption. Although the critical area may include portions distributed over the whole system, it's treated as a single entity.

Trenchlesspedia explains Core Area

Core areas require detailed flow simulations to define problems and may include older parts of a city where sewer lines might consist of segments of the Orangeburg clay pipe. There may be damaged lead pipes, often found around older hospitals, or gravity sewer lines might have suffered changes to their slope as the result of earth movements or unstable subsurface conditions. Simulations allow engineers to account for conditions in the lines and recommend appropriate remedies, including replacement or other rehabilitative measures.

Evaluation of Sewer Condition

To evaluate the sewer system in a core area, the first step is to conduct a thorough video inspection using a closed-circuit television (CCTV) camera to determine the structural and physical integrity of the pipe. For a thorough structural inspection, the pipes are first cleaned thoroughly of all debris and buildup using water jetting or other appropriate cleaning methods.

Cleaning is an important step to get accurate information such as type of pipe material, pipe size, the severity of the defect in terms of cracks, corrosion, collapsed or broken pipe walls, offset joints, tree root intrusion, and projecting lateral connections. Structural assessment should also be done for manholes to check for damage from chemical attack, broken bricks, cracked concrete, and damaged inverts.

Analysis for Inflow/ Infiltration (I/I)

Improper or illegal connections to the mainline from sump pumps and rainwater downspouts can lead to Inflow problems. Infiltration on the other hand is caused by leakage due to cracks in pipes, improper pipe joints, and manholes. I/I can lead to pipe damage and also increase the cost of treatment at treatment plants while reducing its effective capacity.

Capacity Analysis

Pipes in the core area are often subject to overloading as most of them are old pipelines that are designed for lesser loads. Such pipes can fail and cause severe damage to the underground pipeline system and to other utility lines passing through that area.

Capacity analysis can be carried out to determine if the pipe is carrying loads within the designed limits. It can be determined based on the size and slope of the pipe. If population growth is expected in the future, the computed capacity can be compared against future expected sewer flows.

Trenchless Rehabilitation Methods

Once the pipeline evaluation results are out, it becomes easier for contractors to select the most appropriate and cost-effective rehabilitation method. If the analysis shows that the pipe does not need to be replaced, a rehabilitation technique most suitable can be selected. Some of the trenchless rehabilitation methods are cured-in-place pipe (CIPP), mechanical spot repair, chemical grouting, pipe bursting, and sliplining.

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