Stormwater Atlas

Idaho

Idaho Catalog of Storm Water Best Management Practices

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Compare each cited field to the official PDF before relying on it. What this means

April 2020 Idaho DEQ BMP catalog is voluntary statewide guidance that defers to local design standards; Table 5 and §3.6 supply default design-storm/WQv/hydrology methods when local standards are absent. Source text includes an explicit truncation marker ([... DOCUMENT TEXT TRUNCATED FOR LENGTH — middle sections omitted ...]) so many middle BMP fact sheets (roughly after rainwater harvesting design detail through later operational BMPs) were not available for review; TOC and early chapters plus §3.6 remain intact.

Fields not found in document: design_criteria.required_hydrologic_hydraulic_software
Other manuals in Idaho: City of Boise, Idaho

Document Metadata

Jurisdiction level
State

The Idaho Catalog of Storm Water Best Management Practices provides technical guidance for construction site design and selecting storm water best management practices (BMPs) as well as information on permitting requirements for storm water discharges in Idaho.

Section 1 Introduction, Page 1

State
Idaho

Idaho Department of Environmental Quality Water Quality Division 1410 N. Hilton Boise, ID 83706

Cover

Version / edition
April 2020

No. 10. http://vwrrc.vt.edu/swc/april_22_2010_update/DCR_BMP_Spec_No_10_DRY_SWALE_Fi nal_Draft_v1-8_04132010.htm Washington State Department of Ecology. 2012. Stormwater Management Manual for Western Washington. Lacey, WA. Publ. 12-10-030. http://www.ecy.wa.gov/programs/w

p. 131

Adoption / effective date
2020-04

This 2020 BMP catalog provides updated information on storm water regulations and provides additional technical information on selected BMPs.

Section 1.2 Catalog Updates, Page 2

Last revised date
2020-04

No. 10. http://vwrrc.vt.edu/swc/april_22_2010_update/DCR_BMP_Spec_No_10_DRY_SWALE_Fi nal_Draft_v1-8_04132010.htm Washington State Department of Ecology. 2012. Stormwater Management Manual for Western Washington. Lacey, WA. Publ. 12-10-030. http://www.ecy.wa.gov/programs/w

p. 131

Relationship to state manual
independent

This catalog contains voluntary controls that could be formally adopted by a jurisdiction to establish standards... it is not all-inclusive and should be used with other reference sources published by other agencies as appropriate based on local conditions and policies.

Section 1 Introduction / 1.1 Goals and Objectives, Pages 1–2

Design Criteria

Design storm return periods (years)
1-year, 2-year, 10-year, 100-year

While the most frequently used design for flood control and channel protection are the 2-, 10-, and 100-year storms... Table 5. Design storm frequencies... 1 year... 2 year... 10 year... 100 year Used for flood control protection from major storms

Table 5 and Section 3.6.1, Pages 52–53

Water quality volume method
Defer to local flood/WQ design standards when available; otherwise Table 5 guidance: capture first 1/2 inch of runoff (~70–80% of annual runoff volume) or first 1 inch (~90%) as water quality volume / first-flush treatment depth; alternatively require a specified pollutant-removal percentage (e.g., 80% suspended solids). WQv may also be tied to a design storm frequency (6-month, 1-year, or 2-year).

Use local design standards for flood control and water quality control. If local design standards are not available, Table 5 provides a summary... 1/2 to <1-inch rainfall Intended to capture 70%–80% of annual runoff volume... 1-inch rainfall Intended to capture 90% of annual runoff volume... jurisdictions specify a treatment volume, referred to as the water quality volume... first 1/2-inch, 1-inch, or other rainfall depth... or... 6-month, 1-year, or 2-year frequency storm... must have 80% of suspended solids removed

Sections 3.6 / 3.6.2 and Table 5, Pages 52–53

Peak flow calculation method(s)
Rational Method, NRCS TR-55, Continuous simulation (HSPF, HEC-HMS, SWMM), Degree-day method (snowmelt), HEC-HMS energy balance (rain-on-snow)

The rational method and NRCS Technical Release-55 (TR-55) method are simple and widely used for performing single event design storm analysis... continuous simulation models... HSPF... HEC-HMS, and... SWMM... For rain-on-snow events, an energy balance approach using a computer model such as HEC-HMS is recommended... degree-day method

Sections 3.6.3–3.6.3.2, Pages 53–59

Hydrologic/hydraulic software
Not found in document

No evidence cited

Approved BMP categories
Site Design BMPs, Construction BMPs, Postconstruction BMPs, Storm Water Filters (biofiltration/bioinfiltration swales, filter strips, media filters, catch-basin inserts), Infiltration Facilities (trenches, bioretention, porous pavement, vegetated roofs, planters), Detention Facilities (wet ponds, extended detention, constructed wetlands, sedimentation basins, underground detention), Other Structural Controls (oil/water separators, vortex separators, level spreaders), Source Controls, Green Infrastructure / Low-Impact Development, Rainwater Harvesting and Reuse

and limitation information as well as design parameters, construction guidelines, and operation and maintenance recommendations. The most important requirements for successful performance of treatment control postconstruction facilities are proper sizing and regular inspection

p. 41