This page contains storm water related resources which will be utilized in the design phase for small projects with a disturbed area less than 1 acre. This applies to Rules Relating to Water Quality, Effective Dec. 2018 (RRTWQ) Categories:
Trenching (< 1 acre); and
Note: For projects that disturb 1 acre or more of land (Categories 1C, 5 and Trenching (> 1 acre)), see the Design Storm Water Tools (≥ 1 Acre) page instead for applicable design resources.
See below for tools developed to assist in compliance with the City’s RRTWQ and the City Municipal Separate Storm Sewer System (MS4) permit, whose main goal is to prevent storm water pollution from construction sites to Hawaii waters.
Project Categories for Development
Click on the Category Check tool to the right and answer the series of questions to determine your project’s category. At the end, download a PDF that documents your answers and the result. Alternatively, you can click on the second link to the right for a table comparing all of the RRTWQ category criteria.
Before using the Category Check tool, you will need to know:
- If the project will require any trenching, building, grading, grubbing, and/or stockpiling permits
- The total disturbed area (DA) – use the worksheet to the right for help calculating the DA
- The size of the project’s zoning lot
- If land disturbing activities will occur on slopes 15% or greater
- If there is a proposed cut or fill greater than 15 ft in height
- Whether the development will be used for single/two-family dwellings or other uses
Note: Where a development qualifies for more than one project category, the higher project category shall apply unless it meets the criteria for a Minor Development.
Project category is determined by the storm water pollution risk at a site – requirements such as Erosion and Sediment Control Plan (ESCP), Best Management Practices (BMPs) and inspection frequency, differ from category to category. Scroll down for information regarding storm water requirements and project category tools. Let’s work to keep Hawaii’s waters clean, fishable, and swimmable.
Note: If the Category Check tool has determined that your project is either a Category 1C or 5, see the Design Storm Water Tools (≥ 1 Acre) page instead for applicable design resources.
The checklists (prepared by the City’s MS4 Program) and tables available to the right can help you determine if your ESCP includes the appropriate RRTWQ and National Pollutant Discharge Elimination System (NPDES) requirements.
ESCP Design Guides
The links to the right offer design guidance documents that expand on pertinent RRTWQ requirements. These checklists and design requirements guides (Revised Oct. 2019) are aimed to further assist in the development of ESCPs specific to each project category.
Force Account, Line Item, and Allowance Guide
The purpose of this guide is to provide tips and examples to account for the costs of BMPs and compliance tasks through funding mechanisms, such as line items, force accounts, or allowances. Incorporating storm water components allows the contractor to accurately estimate the costs of BMPs and compliance tasks as well as be compensated for construction site pollution control.
Pre-Construction Discussion Points
Before construction begins, it’s important to discuss compliance requirements and determine who is responsible for what. Design and construction personnel, the contractor, and contracted construction managers (if applicable), will all have useful input in this discussion, and coordination is particularly important when more than one party is involved in the completion of a task. These pre-construction discussion points are intended to help usher this conversation and ensure common requirements are covered.