USACE Emergency Earth Levee Section and Seepage Creep Check

ScopeAn emergency earth levee is built to a handful of USACE flood fight rules, and the base width that satisfies the side slopes can be half what the seepage rule requires. Sand fill stands at 1V:3H toward the river and 1V:5H toward the land with a 10 ft top that leaves room for equipment to raise it; clay fill stands at 1V:2.5H on both sides. The calculator builds the section, reports the base width, the cross-section area, and the in-place fill in cubic yards, and lets the top width change for the equipment on hand. A 4 ft levee 100 ft long is a 42 ft base, 104 sq ft, and 385 cubic yards in sand, or a 30 ft base, 80 sq ft, and 296 cubic yards in clay -- almost 90 cubic yards saved. But on a fine-sand foundation the clay section must pass the creep check: water under head seeps beneath the levee, and if the path is too short it carries soil with it and the levee fails from below. The handbook sets the minimum path at 15 times the head over fine sand and 9 times over fine gravel, so the 4 ft clay levee needs 60 ft and has 30 ft; the 30 ft shortfall is the berm, 3 ft or thicker, that lengthens the path, and its fill can erase the saving. Over fine gravel it is still 6 ft short. It does not design a permanent levee, analyze slope stability or through-seepage, address clay over sand, compaction, or berm design beyond its length; loose truck volume is larger by the soil's swell. The USACE Flood Fight Handbook, the USACE district, and the local emergency manager govern.

Formula or tablebase B = top + (z_river + z_land) x H; sand fill 1V:3H riverside and 1V:5H landside, clay fill 1V:2.5H both sides; area = (top + B) / 2 x H; fill = area x length / 27 cu yd in place; clay section on a pervious foundation: required path L = C x H (C = 15 fine sand, 9 fine gravel), berm shortfall = L - B when positive.

Source and editionUSACE St. Paul District, Flood Fight Handbook (2016), Section 3.3, emergency levee sections by fill and foundation and the creep ratio criterion. The USACE district and the local emergency manager govern.

Free accessThe USACE Flood Fight Handbook is a free federal publication; the slopes and creep ratios are stated values.

What governsEstimate. AHJ and licensed professional govern.

API field namesheight_ft, fill, foundation, top_width_ft, length_ft, base_width_ft, area_sqft, fill_cy, berm_shortfall_ft

• Section slopes sand 1V:3H riverside and 1V:5H landside with a 10 ft top; clay 1V:2.5H both sidesUSACE Flood Fight Handbook Section 3.3
• Creep ratio minimum seepage path 15 x head over fine sand, 9 x head over fine gravelUSACE Flood Fight Handbook Section 3.3
• Volume basis in-place cubic yards, no swell or shrinkgeometry