Green and Stormwater Calculators

A number of agencies and organizations have developed stormwater and green infrastructure calculators to assist design professionals in stormwater management and green infrastructure planning, costing and comparison of various best management practices. We've included calculators from the U.S. Environmental Protection Agency, Center for Neighborhood Technologies, Sustainable Technologies Evaluation Program and the Water Environment Research Foundation.

 

State, regional or municipal calculators and programs by educational institutions are also being developed and will be listed as they become available.

 

Tags: Interlocking concrete pavers, UNI Pavers, permeable pavers, PICP, permeable pavement, stormwater, stormwater calculators, green infrastructure, best management practice, EPA, Center for Neighborhood Technologies, STEP, WERF, Water Environment Research Foundation

 

EPAEnvironmental Protection Agency National Stormwater Calculator

The EPA has released their National Stormwater Calculator, a desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the United States (including Puerto Rico). Estimates are based on local soil conditions, land cover, and historic rainfall records.

 

It is designed to be used by anyone interested in reducing runoff from a property, including:

  • site developers
  • landscape architects
  • urban planners
  • homeowners

The Calculator accesses several national databases that provide soil, topography, rainfall, and evaporation information for the chosen site. The user supplies information about the site’s land cover and selects the types of low impact development (LID) controls they would like to use.  The LID controls that the user can choose are seven green infrastructure practices:

  1. Disconnection

  2. Rain harvesting

  3. Rain gardens

  4. Green roofs

  5. Street planters

  6. Infiltration basins

  7. Porous pavement

It is based on the EPA’s SWMM program which has been used for over 40 years and is widely accepted. The SWMM program is the basis of the PC-SWMM PP that was developed by Bill James of Computational Hydraulics for UNI-GROUP U.S.A. It is a free program.

 

EPA NATIONAL STORMWATER CALCULATOR

EPA NATIONAL STORMWATER CALCULATOR FACT SHEET

EPA NATIONAL STORMWATER CALCULATOR USERS GUIDE

EPA NATIONAL STORMWATER CALCULATOR WEBCAST SLIDES

 

 

Center for Neighborhood TechnologiesNational Green Values Calculator by the Center for Neighborhood Technologies

The Center for Neighborhood Technology (CNT) is an award-winning innovations laboratory for urban sustainability. CNT works across disciplines and issues, including transportation and community development, energy, water, and climate change. These stormwater management calculators are quite detailed with parameters for site information including annual rainfall by zip code, design storm, rainfall in inches, soil type, impervious cover, percentages of types of land cover, runoff reduction goals, green improvements, life cycle, curve numbers, coefficients, costs and benefits.

 

GREEN VALUES STORMWATER TOOL BOX

GREEN VALUES NATIONAL STORMWATER CALCULATOR

GREEN VALUES STORMWATER CALCULATOR

GREEN VALUES CHICAGO DOE STORMWATER CALCULATOR

GREEN VALUES CALCULATOR METHODOLOGY

 

Sustainable TechnologiesSustainable Technologies Evaluation Program

This worksheet was developed by the Sustainable Technologies Evaluation Program, Toronto and Region Conservation Authority who have tested UNI® pavers in a number of projects. The worksheet is based on local costs and design for that area, though it may be useful from a comparison standpoint as it features a number of stormwater management practices that can be compared and there are separate costing sheets for bioretention, grass swales, green roof, infiltration chambers, infiltration trench, PICP and rainwater harvesting. When you select a specific stormwater practice, it opens other sheets for that practice that include design and cost information, maintenance and life cycle costs.

 

STEP PERMEABLE PAVEMENT

STEP LID TOOL EXCEL SHEET

STEP LID ASSESSMENT OF LIFE CYCLE COSTS FOR LOW IMPACT DEVELOPMENT STORMWATER MANAGEMENT PRACTICES

 

Water Environment Research FederationWater Environment Research Federation BMP and LID Cost Tools

In a climate of increasingly smaller budgets and competing needs, calculating the whole-life cost of a BMP or LID approach can be key to making decisions about the most appropriate and cost-effective options – and ultimately moving a project forward.  WERF’s suite of modeling tools provides a framework to ease cost estimation for various solutions, factoring in items such as capital expenses, long-term maintenance, and the potential value a project will deliver. These tools, which supply planning-level estimates and can serve as a format for cost reporting, are available for a variety of BMPs and LID options, including green roofs, rainwater cisterns, bioretention facilities, retention ponds, extended detention basins, swales, rain gardens, and permeable pavement.

 

BMP AND LID COST TOOLS WEBSITE

BMP AND LID COST TOOLS FACT SHEET

BMP AND COST TOOLS EXCEL SHEETS

 

State, Regional and Municipal Calculators

State, regional or municipal calculators, as well as programs by educational institutions are also being developed and will be listed as they become available. Please visit our State and Municipal Stormwater and Green Infrastructure Guidance and Incentives and Credit Programs pages for additional information, references and guidance.

Minnesota Minimal Impact Design Standards Calculator

Volume and pollutant reductions given in the MIDS calculator are based on the assumption that the BMP is properly designed, constructed and maintained. Guidance and recommendations for design, construction and maintenance are contained within the individual BMP sections of the Minnesota Stormwater Manual.

 

Minnesota Minimal Impact Design Standards (MIDS) Calculator

Minnesota Stormwater Manual - Wiki

 


 

Santa Rosa, CA Stormwater Calculator

This is an Excel-based calculator is to be used by the designer to determine the quantity of storm water that will need to be treated and/or infiltrated to meet the permit requirements. 

 

Santa Rosa Stormwater Calculator

Santa Rosa Storm Water Low Impact Development Technical Design Manual

 


 

North Carolina State University Biological & Agricultural Engineering - Stormwater

NCSU BAE has developed a number of hydrologic models for permeable pavements, bioretention, green roofs and rainwater harvesting.

 

Stormwater Engineering Downloads

Permeable Pavement Hydrologic Design Model - Excel Sheets

 


 

Oregon State University Porous Pavement Hydrologic Calculator

Oregon State University has developed comprehensive calculators for porous pavements.

 

Porous Pavement Calculators