Abstract: An underwater soil erosion prevention system has a generally rectangular length of material folded at regularly spaced intervals at an angle generally perpendicular to the longitudinal axis of the rectangular length of material, thereby forming sheets. Each sheet contains slits which are generally perpendicular to the fold. The slits begin above the bottom edge of the sheet and terminate below the top edge of the sheet. The sheets contain openings sized to snugly receive an anchor line on either side. To aid in deploying the soil erosion prevention system, an inflatable rollable array with a receiving valve is provided. The array can be rolled together with the underwater soil erosion prevention system, and when ready for deployment, a fluid is controllably inserted into the array through the receiving valve, thereby causing the array and system to unroll. Alternatively, the underwater soil erosion prevention system can be releasably attached to a frame mechanism to facilitate deployment underwater.

Abstract: A ground anchor comprises a generally flat anchor plate folded into a U or V-shape against a resilient bias. The resilient bias may be inherent in the folded portions of the anchor plate, or may be provided by means of auxiliary or plate springs disposed between the folded portions. In the latter, a retaining pin may secure the folded portions together while driving the plate into the ground. A release arrangement shears the pin so that the plate springs open to resist subsequent extraction.

Abstract: An underwater soil retention and reinforcement structure comprises a sequence of synthetic buoyant fronds (11) arranged side-by-side to form a frond line. The frond line is folded back and forth to form an array of fronds, and the successive folded sections (14) of the frond line have aligned openings (20) threaded by at least one anchor line (19) for anchoring the array to the soil bed.

Abstract: A ground anchor adapted to be driven into the ground using a driving tool socket affixed near the leading edge of the anchor is disclosed. The anchor comprises a generally flat plate having a hinged, serrated tail flap. After being driven into the ground the anchor is secured in place immediately, without lifting, when tension is applied to a strap attached thereto.

Abstract: A frond line (10) for filtering particulate material from currents flowing over a river or sea bed comprises a substantially continuous curtain of randomly overlapping elongate buoyant elements (15) extending transversely in a common direction from a longitudinally folded web (35), the base of each element (15) being gripped between the superposed portions of the folded web. A frond mat is produced by combining spaced parallel rows of the frond lines (10) with spaced generally parallel cross-straps (13) to provide an open grid mat structure. Anchoring straps (20) depend from the mat, each strap carrying a ground anchor plate (12) which is driven into the river or sea bed by a powered driving tool. The frond line (10) is produced by laying discrete transverse strips (31) of synthetic buoyant material along the web (35) so that equal lengths extend from opposite sides of the web (35), folding the web (35) longitudinally, and then securing the superposed portions of the web to one another.