Dry swale materials specifications
Link to this table
| Parameter | Specification | Size | Note |
|---|---|---|---|
| Topsoil | Topsoil per MNDOT 3877 | n/a | Characteristic of local site soils |
| Media sand | ASTM C-33 fine aggregate concrete sand | 0.02” to 0.04” | |
| Check dam (pressure treated) | AWPA Standard C6 | 6” by 6” or 8” by 8” | Do not coat with creosote; embed at least 3’ into side slopes |
| Check Dam (natural wood) | Black Locust, Red Mulberry, Cedars, Catalpa, White Oak, Chestnut Oak, Black Walnut | 6” to 12” diameter; notch as necessary | Do not use the following, as these species have a predisposition towards rot: Ash, Beech, Birch, Elm, Hackberry, Hemlock, Hickories, Maples, Red and Black Oak, Pines, Poplar, Spruce, Sweetgum, Willow |
| Check dam (rock, rip rap) | Per local criteria | Size per requirements based on 10-year design flow | Cannot get water quality volume credit when using a permeable check dam |
| Check dam (earth) | Per local criteria | Size per requirements based on 10-year design flow | Use clayey soils with low permeability |
| Check dam (precast concrete) | Per pre-cast manufacturer | Size per requirements based on 10-year design flow | Testing of pre-cast concrete required: 28 day strength and slump test; all concrete design (cast-in-place or pre-cast) not using previously approved State or local standards requires design drawings sealed and approved by a licensed professional structural engineer. Embed at least 3’ into side slopes |
| Filter Strip sand/gravel pervious berm | sand: per dry swale sand gravel; AASHTO M-43 | sand: 0.02” to 0.04” gravel: 1/2” to 1” | Mix with approximately 25% loam soil to support grass cover crop; see Bioretention planting soil notes for more detail |
| Pea gravel diaphragm and curtain drain | ASTM D 448 | varies (No. 6) or (1/8” to 3/8”) | Use clean bank-run gravel |
| Underdrain gravel | per pre-cast manufacturer | 1.5” to 3.5” | |
| Underdrain | ASTM D-1785 or AASHTO M-278 | 6” rigid Schedule 40 PVC | 3/8” perf. @ 6” o.c.; 4 holes per row |
This page was last edited on 4 August 2022, at 16:48.