Back To The Family Handyman
Del.icio.us
Digg
Reddit
Facebook
StumbleUpon
TwitThis
Complete The Lower Basin First
Use a 2-in. hole saw bit and drill holes every 4 in. in the bottom third of the pump basin (Figure C). Repeat the process with a 1-in. hole saw bit for the middle third, then use a 3/8-in. bit for the top third.
Remove sharp objects from the bottom of the basin, then lay in the underlayment and liner. Calculate the size carefully and cut the underlayment first. Then cut and fit the liner so it is tucked in all corners and extends about 2 ft. out of the hole in all directions. With the pump basin in place, insert the pump, connect the water line and lay it in place to ensure it will reach the top of the upper pool.Add layers of stone around the basin and top with the lid (Figure C).
TIP: If you live in a freezing climate, make sure the pump and hose are easy to blow out or remove.
Dig Out (or Build) a Long Staircase
First, at each waterfall location, dig down to the approximate depth of the drop you desire or build up the fall if you’re working above grade. This gives you a streambed depth target. Now move to the bottom of the stream and carve a 2 to 3-1/2 ft. wide streambed 6 to 8 in. deep, sloping upward as you dig upstream to meet that streambed depth target at each waterfall. Then dig out shallow pools below waterfalls as needed (Figure A) to slow the water flow.
Since we built above ground for the upper section of the stream, we next added a level row of stones for waterfalls No. 1 and 2. Pick the height you desire. Use 6-in. tall stones to frame the banks. Also finish compacting a gravel and dirt mixture to the inside and outside of the upper pool stones. Then tamp down the upper pool area and the streambed.
Lay the Liner and Position Waterfall Stones
Position the fabric underlayment and liner to extend from the lower basin to the upper pool, with slack at the base of each waterfall, because placing boulders can stretch and rip a tight liner. Place decorative boulders at the side of each waterfall, and add an extra piece of rubber liner underneath each heavy stone to protect the base liner.
TIP: Pick stones with fractures and broken edges to place under waterfalls for more water sound and movement.
For stable, above-ground stream edges, backfill the edging stones with a gravel and dirt mixture and compact it. Next, lay the final piece of underlayment and liner in the upper pool so it tucks in at all corners and extends 2 ft. out in all directions. There’s no need to tape the liners to each other; just make sure the top liner overlaps the liner underneath it by 1-1/2 to 2 ft. Then add the top layer of stones around the upper pool.
Add Spill Stones and Foam the Gaps
Once you place the decorative boulders at the waterfall locations, place all the flat spill stones.Apply black expanding foam sealant, designed for ponds and waterfalls, to the underside to adhere them to the rubber liner. Now fill all gaps with stones to force water to go only over the waterfall. Then apply foam sealant to all sides and to the underneath of each spill stone to create a good seal.
After the foam has dried for 30 minutes, take your garden hose and run water down the stream. Look for any water trails (leaks) along the spill stone edges and underneath. Fill any leaks with more foam and repeat until all water goes over the top of the spill stones.
Add Gravel and Clean the Stream
The final construction step is to place steppingstones in the middle of the stream to make it inviting for people, birds and pets. Then carefully layer in gravel to cover any exposed liner.
Spray down the entire stream area with a garden hose nozzle until the water level rises above the gravel in the bottom basin. Now power up the pump and direct the pump hose away from the stream. Keep washing down the stream and rock until the water from the pump hose runs clear. Then insert the pump hose into the upper pool (make sure it is hidden), and finish your stream by trimming and covering any rubber liner that shows.
Now it’s time to take that favorite seat, with a cold beverage in hand, and relax to the soothing sounds of your new stream.
Pump Sizing
Submersible pumps are rated by gph (gallons per hour) at a specific discharge height (known as head or lift). To calculate the gph you need, figure 150 gph for each inch of your widest waterfall. Next, to figure the head/lift you need, calculate the distance your water line travels from the pump to the upper pool (measure vertical and horizontal; 10 ft. of horizontal distance = 1 ft. of vertical rise). Look for a high-quality pump (bronze, brass or stainless steel; not a cheap sump pump) that can exceed the gph and lift you need.
Advertisement 
