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 apply to dry swales. Check dams (pressure treated and natural wood) and rip rap apply to wet swales.