Civil Engineering Grading Drainage Plans


Most builders only focus on windows, roofs, and other openings to prevent water from getting into the home. But managing water flowing on the entire property is equally important. For that reason, it’s important for every construction project to include a grading plan.

In essence, land grading is an activity that falls under the field of civil engineering.  It involves various tasks like soil movement, drilling as well as ground grading. More notably, they’re accountable for mapping out the grading and drainage plan before the project begins.

But, what exactly is a grading & drainage plan? Well, that’s one of the things we’ll be discussing in this article. That said, let’s get right into it!

What is a Grading and Drainage Plan?

Drainage and lot grading plan are needed to get a construction permit from the municipality. In construction, grading refers to shaping the landscape of the land area. This is intended to guide the surface runoff away from the building structures on the site. Moreover, the surface runoff must be directed to a street, lane, or an approved drainage system.

Typically, a grading plan is a blueprint that shows the lot’s slope in 5-ft increments. Also, it shows existing grades, your property, the proposed location of the new house, and its dimensions. More notably, it shows proposed grades or how the ground around the structure will slope. At the same time, it should include; easements, fences, and drainage swales.

This plan ensures that the construction of a new structure is done in a manner that allows proper surface drainage. While preventing any negative impact on the neighboring landowners. Moreover, it provides the builder with specific details for managing or inspecting the grading contractor. As a result, this will help the builder reduce the chances of callbacks. In addition, it will give them better control over the costs associated with removing or hauling earthwork from the site.

Implementing a Grading Plan

As we’ve already stated, a grading plan guides water away from your lot. It emphasizes the landscape of your property, especially the height of the soil and house. There are 2 things you need to consider when creating the final land grading plan for a commercial building or home. First, water should be moving down, then away from the floor. Secondly, the runoff should exit the property and get into a storm drainage system.

What happens if the land isn’t graded properly?

Improper land grading can have a certain negative impact on your property and neighboring properties. For instance, rainwater will run towards your home, rather than running away from it. As a result, your home’s foundation will be at risk for damage because of the moisture.

Besides, hydrostatic may build up against the building’s base or wall. Basically, hydrostatic pressure refers to the weight of water pushing the wall. It can cause various problems like structural damage, soil erosion, or foundation cracks.

Another negative impact of poor land grading is that it causes problems to the neighboring property. As an example, if the surface runoff flows towards the adjoining property, it can cause soil erosion or even flooding. In this case, the contractor and the property owner may be held accountable for any loss that occurs due to this issue.

To avoid these problems, make sure you follow the grading plan when preparing the finished grade. Also, you can adopt other specific techniques creating swales to redirect groundwater. Alternatively, you can grade slopes that direct water away from the building. Or come up with an accurate plan demonstrating how much soil you need to add or remove from the site.

Who prepares a land grading plan?

A grading plan should be created under the supervision of a licensed civil engineer or architect. More importantly, the design must be approved and signed by the architect/ engineer before using it to pull a permit.

In most cases, county codes require that a grading plan should be designed by a civil engineer. Especially if the grading project involves about 2,000 cubic yards of earthwork. However, the local planning department requires grading plans for any complex project, even if it involves less than 2,000 cubic yards.

Although architects can draw up a grading plan, the best practice is to have them prepared by civil engineers. This is because engineers are more knowledgeable on the unique techniques that can be incorporated into the plan. Besides, engineers can create a detailed grading plan showing the quantity of soil that needs to be brought in or extracted from the site.

Supervising the final grade

There are certain principles you need to consider when inspecting and planning for the final grade.

First, most of the grading activity should be performed over the dry season. This will eliminate the need to re-grade the land at a later stage. More importantly, this prevents soil erosion that may occur during the course of the project.

Secondly, re-use the earthwork that’s excavated from the construction site to prepare the final grade. At the same time, spray extra stockpiles of earthwork with hydraulic mulch or cover them. This will prevent excessive runoff and protect the soil from erosion.

In addition, make sure that proper backfilling is done near the foundation. Especially if the final grade is near the wall cladding or most of the foundation is above the grade. This will help to get rid of paths that termites may use to enter your home. Moreover, it will protect the building from moisture issues that may occur in the future.

Lastly, the site supervisor should closely monitor the activities of the grading crew. More notably, the approved grading plan should be adhered to during the entire project. This will help to prevent various issues, saving time and money for everyone involved in the project.

Final Word

Overall, following a grading plan carefully will help the build avoid any problem. Even better, it will protect the new building structure from avertible water and drainage issues. Therefore, a grading and drainage plan is an important document to have before you start a land grading project.

If you want help with a grading plan for a project in California, contact InnoDez Design & Engineering. Our civil engineers will happily design the grading plans for your project!

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