HomeMy WebLinkAbout2021.07.22_1411 Crystal Lake Stream Margin Exemption Review_EngineeringStream Margin Exemption Review | 1411 Crystal Lake Road | LPA-21-053 | 07/22/21
Engineering Department Comments
General Comments
What special design considerations have been taken to ensure the pool is not impacted by
fluctuating groundwater levels. What is the groundwater depth in this area?
Answer:
Hp Kumar in June of 2017 provided a soils report for the construction of the house. Both test
pits at 12’ and 13’ did not hit ground water. The pool excavation will be approximately 5.5’
maximum. The pool has been designed with a hydrostatic value in the floor.
How is stormwater runoff accommodated so that the pool doesn’t overtop to the river? What
happens during a larger storm event? Is there a drain to prevent overtopping and where does
the drain connect to?
Answer:
The pool has been designed with a drain in the cover vault (typical). This keeps the pool from
overflowing. Pool drain are typically designed to connect to sanitary system of the house.
How will the pool and the rock wall be constructed without impacting the 15’ setback? Provide
the means and methods for installation.
Answer:
Our intention for the excavation of the Smallwood Pool would be test a small section of the
pool area back from the actual edge of the final excavation to understand if the bank will hold
for our relatively shallow excavation. If we feel that it is unlikely that the excavation wall will
hold we will need to install some micropiles along the area that we are closer to the
envelop. We would have B&Y or Rock Solid do grouted micropiles to support the limits of the
excavation. This would allow us to have a vertically supported excavation wall.
When the building permit is submitted, clearly show how any leaks to the pillow bladder
wouldn’t drain to the river but would drain back to the pool. Provide spot
elevations/contours/drainage arrows to prove this will not drain to the river.
Answer:
Client and pool builder have agreed to abandon the bladder idea and use a water truck to haul
the water offsite once it is stabilized.
Will this pool have a hard cover? If so, where does the runoff for this new impervious area
drain? Is there capacity in the property’s stormwater system for WQCV treatment and/or
detention if required? If there is no hard cover, how is drainage accommodated in the summer
and the winter?
Answer:
The pool will have an automatic safety cover. We have designed a new rain garden below the
pool. The water calcs and sections have been produced by Sopris Engineering and are
attached with this document.