Open vegetated swale materials specifications
Open vegetated swale materials specifications. See footnotes for which swale type the parameter applies to.
Link to this table
| Parameter | Specification | Size | Note |
|---|---|---|---|
| Dry swale soil | USCS; ML, SM, SC | n/a | soil with a higher percent organic content is preferred |
| Dry swale 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 |
| 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 |
| Rip rap | per local criteria | size per requirements based on 10- year design flow | |
All parameters applies to dry swales. Check dams (pressure treated and natural wood) and rip rap apply to wet swales.