Most frequent questions and answers
The coefficient will vary based on the ideal material for the project. Many of our HDPE liners and GRP liners have a Manning’s of 0.009, while some of the metal plate liners can be as high as 0.035. We also offer an internally-corrugated HDPE—which has a Manning’s of 0.028–0.032 —and works well for meeting stringent aquatic life needs (which are often required by the DEP and other environmental authorities).
Often, the preferred choice for annular space grouting is low-density cellular concrete (LDCC). Other materials, such as flowable fills, can be used in certain instances. The DLVEWS team can recommend the best material based on your project’s specifications, so please ask us for details.
Depending on the material, typical minimum cover amounts are 1 to 2 feet. Maximum cover amounts can range from 30 feet to more than 65 feet. We will check these for you, and will determine the best material.
If we need to order the materials, you can expect the following approximate lead times:
HDPE: 3–4 weeks
CMP: 4–6 weeks
GRP: 8–10 weeks
Please ask us for specifics when we discuss your project.
Culverts do not typically require a pressure-rated joint. Our liners are used for structures such as sanitary sewers, which may require a pressure-rated joint. In this case, our HDPE and GRP solutions have joints that can range from zero to 30psi. We invite you to discuss this with your DLVEWS representative during the design and specification process.
We pride ourselves in offering a very hands-on approach. We will visit job sites with engineers and owners alike, will review plans and specifications, and work as a team to determine the best liner solution.