CAC Stream and Waterfall Construction 1 — Questions and Answers
Question 1: What is the primary purpose of installing a berm when constructing an aquascape stream?
- To direct water flow and prevent seepage outside the liner (Correct answer)
- To add decorative elevation to the surrounding landscape
- To create a habitat for aquatic turtles
- To support the weight of large boulders
Correct answer: To direct water flow and prevent seepage outside the liner
A berm channels water within the stream course and prevents liner water from escaping into the surrounding soil.
Question 2: Which underlayment material is most commonly placed beneath EPDM liner in a stream or waterfall to prevent punctures?
- Landscape fabric
- Geotextile underlayment padding (Correct answer)
- Concrete board
- Sand layer
Correct answer: Geotextile underlayment padding
Geotextile underlayment padding is specifically designed to cushion and protect EPDM liner from sharp rocks and roots underneath.
Question 3: When stacking boulders to form a waterfall weir, which placement technique best prevents water from channeling behind the rocks?
- Stacking boulders dry without mortar
- Embedding the base of each boulder into foam-sealed liner (Correct answer)
- Setting boulders on a concrete footing
- Leaning boulders against the hillside at an angle
Correct answer: Embedding the base of each boulder into foam-sealed liner
Embedding boulder bases into foam-sealed liner ensures water flows over and around rocks rather than seeping behind them and off the liner.
Question 4: What is the recommended minimum overlap of EPDM liner at stream section joints to prevent leaks?
- 6 inches
- 12 inches (Correct answer)
- 24 inches
- 36 inches
Correct answer: 12 inches
A 12-inch overlap at liner joints provides adequate coverage to prevent water from seeping through connection points as the ground shifts.
Question 5: In a typical pondless waterfall installation, where is the primary water reservoir located?
- In an above-ground holding tank
- Buried beneath the base of the waterfall in a gravel-filled basin (Correct answer)
- Inside the pump vault only
- In a cistern placed uphill from the waterfall
Correct answer: Buried beneath the base of the waterfall in a gravel-filled basin
A pondless waterfall uses a gravel-filled underground basin at the base to store water while hiding the reservoir from view.
Question 6: Which foam product is used in aquascape construction to seal gaps between rocks along a stream or waterfall?
- Silicone caulk
- Expanding polyurethane foam sealant (Correct answer)
- Hydraulic cement
- Spray-on rubber coating
Correct answer: Expanding polyurethane foam sealant
Expanding polyurethane foam sealant (such as black waterfall foam) fills voids between rocks, directing water flow over the intended surface.
Question 7: When excavating a stream bed, what slope is generally recommended per linear foot to ensure consistent water movement?
- 1/8 inch per foot
- 1/2 inch per foot (Correct answer)
- 2 inches per foot
- 4 inches per foot
Correct answer: 1/2 inch per foot
A slope of approximately 1/2 inch per linear foot provides enough gradient for natural-looking water movement without causing excessive velocity.
CAC Stream and Waterfall Construction 1
What is the primary purpose of installing a berm when constructing an aquascape stream?