response to engineering (2) D ENGINEERS, LLP.
c O 411 Union Street
PARTNERS n Schenectady,NY 12305
JOSEPH J.BIANCHINE,P.E. '1 1 518-377-0315 Fax 518-377-0379 DEDICATED
LUIGI A.PALLESCHI,P.E. w RESPONSIVE
MARK C.BLACKSTONE,P.L.S. www.abdeng.com PROFESSIONAL
May 17, 2021
Re: Native Development Queensbury
24 Native Road
Town of Queensbury
Project#4899A
Laura Moore
Zoning Administrator and Code Compliance Officer
Town of Queensbury Planning& Development
742 Bay Road
Queensbury, NY 12804
Dear Laura:
In response to the comments (in italics) of Chazen Companies. letter dated May 13, 2021 we
respond as follows (in bold):
Stormwater Management and Erosion and Sediment Control
1. Comment 1 of Chazen's letter dated Apri101, 2021 stated that a fill review of the Stormwater
Management Report and HydroCAD model could not be performed at that time. The Applicant
has provided a revised Stormwater Management Report and HydroCAD model for review.
Chazen's comments relating to the Report and Model are below:
In response to la regarding the infiltration trenches, the applicant clarified the location and
design. It does not appear that infiltration testing was performed for the infiltration trenches; and
testing shall be performed, and results provided in accordance with the NYS SMDM. Further, the
HydroCAD model appears to suggest that runoff to the infiltration trench would be via sheet
flow, however the grading plan does not appear to match that. Two sections of the infiltration
trench appear to abut retaining walls; if the retaining wall design includes underdrains, then
those underdrains shall be included in the infiltration trench HydroCAD model. It appears that
the retaining wall designs will be provided at a separate time. The retaining wall design will need
to take into account any influences by the infiltration practice. The retaining wall scales at 2 feet
wide on the plans but is modeled as 3 feet wide in the HydroCAD model. The Applicant shall
indicate locations of snow removal on the gravel road.
The infiltration trenches are now shown as 3' wide to match the HydroCAD model.
In response to comment Ic and Id regarding infiltration testing, it does not appear that the
number of infiltration tests performed meets the NYS SMDM requirements; the FAQ states:
Appendix De Concept Design Testing requirements notwithstanding,DEC accepts as
complying with the department's technical standards a minimum of one test pit/boring and
one infiltration test for every 5000 square feet of basin area,with no fewer than four test
pitfboring and infiltration tests per facility. The area should be divided to equal sub-areas,
tests performed in the center of each sub-area,the lowest and highest numbers discarded,
and an average taken of the remaining values. For areas greater than one acre,an additional
four tests for each additional acre need to be performed.
For instance, the large infiltration basin has a surface area of-38,000 square feet, which
according to the FAQ would require 8 tests pits/boring and one infiltration test. Also it does not
appear that the soil test results were included on Sheet 3. The Applicant to perform sufficient test
pits/borings and infiltration tests per the NYS SMDM and FAQ.
Several test pits were performed and the soils are very consistent throughout the entire site.
Infiltration testing at each location also showed similar results. We will perform additional
test pits and percolation tests on a lot-by-lot basis.
Further, note 7 on sheet 3 states that the fill material infiltration rate shall be confirmed by a
geotechnical engineer after placement and be equal to or greater than %"per hour, but the
Applicant is modeling an infiltration rate of 5"per hour. The Applicant to revise accordingly.
Further, the Loucks report indicates a groundwater level 2.5 feet below Test Pit#1, however the
report does not appear to indicate what the existing grade was at Test Pit#1 and the map is too
small to discern the elevation. The Applicant to provide the existing grade for all of the test pits in
the geotechnical report.
Note 7 on Sheet 3 has been revised to state infiltration rate greater than 10 inches per hour,
which is conservative compared to the design infiltration rate. All test pits are now shown
on the revised plans,Sheet 3.
2. In response to comment 3 of Chazen's letter dated April 01, 2021, the Applicant sent plans
(progress print 4122121)and information to the NYS DEC, who responded on April 27, 2021
(email attached for reference). The DEC stated that the volume calculation was not verified but
presented as slightly under 3 million gallons. While it is appears likely that the volume intended
to be impounded will be less than 3MG, it is noted that the Pond 3P stage/storage does not
extend to an elevation of 364 (as such some volume in the stormwater model is unaccounted for).
As such, the Applicant shall update the model to include the missing storage information and
ensure that the volume proposed to be impounded remains less than 3MG.
The model has been updated to show volume less than 3 MG up to elevation 364. See
attached calculation.
3. In response to comment 4 of Chazen's letter dated April 01, 2021, the Applicant provided a
USGS StreamStats report and reduced the culvert to 36"diameter. Subcatchment 16S represents
the offsite tributary area and the 100 year storm HydroCAD model 16S produces 80.2 cfs;
however, the StreamStats report shows the I-percent(100-year storm)peak flow rate of 284 cfs.
The Applicant to clarify or revise accordingly.
Specific data(as highlighted in red) was used in the HydroCAD model. The HydroCAD
model has been updated accordingly. See appendix in Stormwater Management Report for
Stream Stats report.
4. In response to comment 5 of Chazen's letter dated April 01, 2021, the Applicant states, "The
Applicant would like to clear the entire site, install Town road and utilities, as wells as install
culvert pipe and grade the stormwater management area for Phase 1 and 2. Erosion and
sediment control plans has been revised for clarity for these two initial phases. All other phases
will be done on a lot-by-lot basis,"
Clearing of the entire site would alter the hydrologic and hydraulic conditions from pre- to post-
development—a condition for which is not included in the HydroCAD model or stormwater
analysis. Clearing of the entire site would most likely be considered land disturbance and
therefore would require coverage for the entire site. Based on the erosion and sediment control
plan proposed tree line it would appear that the entire site is proposed to be cleared and
grubbed. The Applicant to clarify exactly what is proposed on the lots not in Phase 1 or 2. A full
review of the stormwater controls, ESCplan, and SWPPP requirements will be performed once
this is clarified.
The Applicant intends to cut all of the trees and leave stumps in place until further
development on each lot. The roadway and stormwater basin will require stump removal
W U DD ENGINEERS,LLP
as identified in Phase 1 &2 on the erosion control plan. Additional note to leave stumps in
place on each lot until future development has been added to Sheet 4 of the revised plans.
5. In response to comment 7 of Chazen's letter dated April 01, 2021, the Applicant provide a
response to comments from the geotechnical engineer. Chazen's comment on the geotechnical
report is below:
a. In regard to 7e, the geotechnical engineer's response was that ABD would provide
calculations in support of the armored slope, however it does not appear that ABD
provided a quantitative analysis. The Applicant to provide accordingly.
ABD discussed this comment with Geotechnical Engineer on May 14,2021. Geotechnical
Engineer stated all slopes are 1 on 3 and do not require armored slopes. His intent was to
armor the outlet pipes with riprap,which we have provided on the final site plans for
review.
6. In response to comment 8 of Chazen's letter dated April 01, 2021, the Applicant provide a
forebay and infiltration basin detail, however it is conceptual in nature. The detail shall
incorporate the recommendations from the geotechnical report and prescribe how the contractor
is to prepare the infiltration soils vs. the embankment soils. It should be noted that the
geotechnical report appears silent on how to prepare the fill soils in the infiltration basin (which
is referred to a detention basin in the geotechnical report). In our opinion, sufficient detail is not
provided to ensure the contractor building the basins,forebays, and embankment according to
the geotechnical report. The Applicant to revise accordingly.
ABD discussed this with Geotechnical Engineer on May 14,2021. No special compaction
requirements are needed to construct the forebay and infiltration bottoms. A note has been
added to the plans for further clarification on construction methods.
7. In response to comment 9 of Chazen's letter dated April 01, 2021 the Applicant referenced the
soil test results. It is noted that sheet 3 indicates that the fill material infiltration rate shall be
confirmed by a geotechnical engineer after placement, which is in accordance with the NYS DEC
guidance mentioned in comment 9 of Chazen's May 14, 2020 letter. The Applicant shall note the
Town prior to the geotechnical engineer performing the infiltration tests, such that the Town can
witness if they so choose. The results shall be provided to the Town. The number of infiltration
tests shall conform to the NYS SMDM and FAQs.
Note#7 has been revised to include testing notification to Town.
I
8. In response to comment 12 of Chazen's letter dated April 01, 2021, the Applicant states "Full
retaining wall design will be provided at the appropriate time. The location of the walls have
been revised to provide better constructability. Please note, we recommend Redi-Rock and a
typical detail is provide on the plan for reference." The retaining walls will be reviewed once
submitted. Detailed site plans will need to be provided with the retaining wall design to review
constructability and feasibility of infiltration practices abutting the walls.
So noted.
9. In response to comment 18 of Chazen's letter dated April 01, 2021, the Applicant states that
the 36"culvert is capable of conveying the 25-year flow and the 100-year flow and referenced
the HydroCAD model. There are comments remaining on the results of the StreamStats report
and once those are revised the culvert model will be reviewed.
See response to comment#3 above.
10. In response to comment 19 of Chazen's letter dated April 01, 2021 regarding documentation
relative to endangered and threatened species, the Applicant stated that afield request has been
submitted to the Town for this documentation and a letter will be provided once received. The
Applicant to provide once received.
DD ENGINEERS,LLP
Will provide,once received.
11. In response to comment 33 of Chazen's letter dated May 14, 2020 and comment 20 of
Chazen's letter dated April01, 2021, the Applicant states, "The wetlands are now clearly
indicated as federal wetlands. The delineation was performed by William H. Smart Engineering.
Smart Engineering is obtaining the necessary documentation. " The applicant to provide
documentation that the wetland delineation has been validated by the US ACOE.
Will provide, once received.
12. In response to comment 22 of Chazen's letter dated April 01, 2021 the Applicant stated that
they will obtain this information. The Applicant shall revise the plans to inchtde existing septic
systems and water wells for all adjoining properties.
The Applicant is gathering this information and will provide them once received. This
should not affect the current subdivision plans as each lot will go through separate site plan
review.
13. The Infiltration basin pond 2P in the HydroCAD model has a basal surface area of 38,845
(359.25), however our cursory calculations show approximately 1,500 square feet less. The
Applicant to clarify or revise accordingly, and the discrepancy may be the pretreatment area for
the catch basin outlet.
Correct. The new pretreatment area that was recently added was needed and it reduced the
bottom infiltration area. The HydroCAD model has been revised accordingly.
14. There still appears to be a small sliver of land on the western property line that is to be
cleared but is not within any subcatchment boundary. The Applicant to revise accordingly.
The small sliver is now included.
Enclosed for resolution to approve the Subdivision and Site Plan are the following items:
1. Two (2) copies of the revised Subdivision and Site Plans (REV#4 05/17/2021).
2. Two (2) copies of the revised Stormwater Management Report and Stormwater Pollution
Prevention Plan(REV 05/17/2021).
3. Basin volume calculation to elevation 364 (response to comment#2).
Electronic copies of the materials listed above will also be provided to you via email. We believe
the responses to the TDE comments have been adequately addressed for the May 18, 2021 Planning
Board meeting. Should you have any questions or need anything further, please do not hesitate to contact
me.
Very truly yours,
ABD E GIN/EERS�/L//L/JP
uigi A. Palleschi, P.E.
Partner
LAP:cly
encl.
cc: Tim Barber(Native Development Assoc., LLC),w/encl. (via email)
Jon Lapper, Esq.,w/encl. (via email)
Sean Doty P.E. w/encL (via email)
4899A-05172021
I
n
W U D ENGINEERS,LLP