grading & drainage plans
Whether you're building, remodeling, or improving your property, proper grading and drainage help protect your home and meet Maui County permit requirements. Green Trees Engineering prepares grading and drainage plans for residential projects across Maui, providing practical designs and guidance through the permitting process from start to finish.
MInor grading permit
A minor grading permit is required in the County of Maui for projects exceeding 100 CY or 4 feet in vertical height, but under 1 acre in total disturbed area. Within the SMA, a minor grading permit is needed for projects exceeding 50 CY or 2 feet in vertical height. Green Trees Engineering will answer all your grading permit questions for you, and can submit the permit on your behalf.
major grading permit
A major grading permit is required for projects with over 1 acre in total disturbed area. This will be likely be required for subdivision work, large ag parcels, and mid sized commercial projects. A major grading permit is significantly more extensive than a minor permit, as it requires stormwater to be retained onsite. It also requires working with the National Pollution Discharge Elimination System (NPDES), obtaining a Storm Water Pollution Prevention Plan (SWPPP), preparing a drainage report, and working with the State Historic Preservation Division (SHPD). We’re happy to put together everything you need for a major grading permit, and handle the permitting side of things too!
stormwater mitigation
Stormwater causes a lot of issues on Maui, and we’re here to help mitigate the negative effects through thoughtful engineering design. Drainage reports are frequently done in association with a major grading permit, and help determine the amount of stormwater that needs to be retained onsite. We can also perform drainage analysis for an existing site that’s having a flooding issue, and make recommendations to mitigate the problem. Please don’t hesitate to reach out. Green Trees is happy to help!