2017.11.29 Dolph Rotfeld Engineering MemoDolph Rotfeld Engineering, P.C.
M E M O
TO: VILLAGE OF RYE BROOK PLANNING BOARD CHAIRMAN
ROBERT GOODMAN
FROM: Anthony Oliveri, P.E.
SUBJECT: 900 King Street Redevelopment
PUD Concept Plan and Preliminary Site Plan
DATE: November 29, 2017
With regard to the above mentioned project, this office has received and reviewed the
following:
1. Plan entitled: "PUD Concept Plan and Preliminary Site Plan, 900 King Street
Redevelopment", prepared by JMC, dated 10/26/2017;
2. Stormwater Pollution Prevention Plan prepared by JMC, dated 10/26/2017;
3. Draft Technical Memorandum, dated 10/26/2017;
Our preliminary comments are as follows:
1. Zoning and parking analysis was not reviewed by this office and should be
reviewed by the Village Building Department and Village Planner.
2. The proposed water main would be required to be a public water main extension
due to the fact that multiple units are being served. The water main will need
approval from the Westchester County Department of Health and Suez Water. At
this time no additional information or analysis has been provided with regard to
pressure and water capacity available to the site and the impact on "The Arbors".
3. Existing water / sewer demand calculations (30,000 gpd) are incorrect in that it
assigns 15 gpd per employee plus an additional 15 gpd per employee of the
building due to food service being offered. However the NYS Design Standards
only assign additional sewer demand for food services based on seat count not
the entirety of the building employee count; this would reduce the existing water
demand estimates to less than 20,000 gpd.
4. The proposed water / sewer demand calculations (49,570 gpd) are incorrect in
that it should utilize a more conservative estimate of 150 gpd per living unit in
addition to the 15 gpd per employee. Also consideration should be given to any
food use proposed for employees. This would result in a total of at least 67,410
gpd for the proposed project. This estimate along with the adjusted existing
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November 29, 2017
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conditions estimate yields a potential increase of over 40,000 gpd in water
demand and sewage flows.
5. It is unclear who has produced the "Technical Memorandum". The engineering
data must be submitted by a licensed professional engineer and provided as
appendices to the report similar to the SWPPP.
6. The proposed sewer main would require Westchester County Department of
Health approval as a public sewer main extension. A detailed engineering report
and analysis of the downstream sewer capacity is required to confirm the
statement in the Technical Memorandum that " The existing main....is expected
to be able to serve the proposed project". This analysis may require video
inspection as well as flow monitoring to accurately determine capacities
available.
7. A much more detailed phasing and construction sequence must be included on
the plan and in the SWPPP. the project appears to propose the disturbance of
approximately 13+ acres in one phase. Sediment and erosion control measures
for such a large disturbance (>>5 acres) must be carefully planned and detailed
on the plan. Consideration can be made to phase parts of the construction such
as the town houses, to limit open disturbance. This plan must be further
developed.
8. The sediment and erosion control plan seems to lack any means of temporary
sediment filtering as well as other standard BMP's such as concrete wash out
areas.
9. Percolation tests as well as deep test pits must be performed to demonstrate the
viability of the proposed infiltration galleries with respect to infiltration properties
and groundwater elevations. Minimum infiltration rates must be demonstrated for
infiltration practices to be viable.
10. The SWPPP should contain pertinent soil maps in the report.
11. The SWPPP must address the downstream condition and discharge point of the
existing storm system to ascertain it's current state of repair and functionality.
Impacts on downstream areas must be analyzed.
12. The SWPPP hydrologic calculations seem to leave out an existing 15" diameter
culvert at the existing detention pond outlet control structure.
13. A more detailed site plan review will be completed upon submission of a site plan
application and responses to the above comments.
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November 29, 2017
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We will be happy to continue our review once additional information is received,
Thank You
C: M. Nowak M. Mohamed
C. Bradbury M. Izzo
J. Gray