Helix Pond Design Guide April 14th 2014 | Page 9

COPING STONE WATER LEVEL Detail D 12” Under Gravel Suction Grid – When installing an GRANITE ROCK under gravel suction grid we are typically using a 2" manifold assembly for the suction grid with a series of three 3/8" holes every 6" across the bottom of the suction grid. We recommend using a 6" layer of 3/4" ROUND gravel covering the top of the suction grid by approximately 2". All ends of the manifold will be capped and each cap will have one 3/8" hole drilled at the bottom side of the cap. 12” 48” 30” 52” 3/4” ROUND GRAVEL 6” 1” AIR RING GEOTEXTILE UNDERLAYMENT 2” MANIFOLD SUCTION GRID 45 MIL E.P.D.M. LINER COPING STONE Detail E Dedicated Koi Pond – Since the Dedicated Koi Pond will not have any rocks to support the walls of excavation we suggest taking proper measures to create support for your coping stones so the edges of your pond do not collapse. In this case we have described a concrete bond beam around the perimeter of the pond to support large coping stones that will frame the water’s edge. Notice the excavation is different than all the other excavation details with a curved bottom wall transition that tapers towards a bottom drain. This detail may not be necessary in all soil conditions and may not be adequate in sandy conditions or depths greater than 48". WATER LEVEL 9” #4 REBAR 8” 16” 36” 48” CONCRETE BOND BEAM GEO-TEXTILE UNDERLAYMENT 45 MIL E.P.D.M. LINER BOTTOM DRAIN ATTACHMENT 8” TO 12” ROUND PEA GRAVEL MARGINAL AQUATIC PLANTS 12” 12” GRANITE BOULDERS 2” PVC BOG MANIFOLD 45 MIL E.P.D.M. LINER 12” 36” SMOOTH GRAVEL UNDERLAYMENT Detail F Active Bog Plant Shelf – When installing an Active Bog Filter we want to have the same excavation detail as the Static Bog Plant Shelf in Detail B only a little deaper because we are making room for a manifold assembly of PVC pipe we will be installing at the bottom of the shelf. We will be pumping water into the bottom of the plant shelf and upflow water through the gravel bed and aquatic plant roots to greatly improve your pond’s filtration capacity. The manifold assembly we build out similar to the Under Gravel Suction Grid Detail D. We recommend using ROUND ornamental gravel no smaller than 3/8" and no larger than 3/4". The depth of the gravel bed should be a minimum of 8" and maximum of 12". 9