No preview available
HomeMy WebLinkAbout2006-06-21 r �, •_ „.. r° , Al .. n T. Fulkerson , L. S. _ _ 1 _ �� David A. Herrick, P. E . LI T n y • , Lee Dresser, L. S. ! 1__• _ _• �_ Y .L IL_E��_, P �.. v� / ' Frank L. Santelli , P. E . • rew J. Sciarabba, P. E . • Engineers and Surveyors Darrin A. Brock, L. S. June 21 , 2006 Ms . Nancy Loncto , Chair Town of Lansing Planning Board Box 186 Lansing , NY 14882 Re : June nth Meeting Agenda Dear Ms . Loncto , We've reviewed the following two projects that are expected to be on the Planning Board Agenda for the June 26th meeting and offer the following comments : Cayuga Way Subdivision — Sketch Plan 1 . Highway and Water System : a . The proposed road configuration requires centerline slopes in excess of 10% . Refer to the centerline profile for Road A. The Engineer must indicate how the grading can be modified to mitigate this condition . b. The Engineer should contact us to coordinate the temporary use of the Town 's booster station constructed in Pheasant Meadow and future connections to a higher pressure tank grid . As mentioned in previous correspondence the Town- is interested 'in aconnection from the tahk site • to the main proposed on. Grandview Drive . c. The re-configured lot layout along Placid Terrace in the Lakeview Subdivision will require ' . agreements that are likely critical to completing a through street. It recommended that-these agreements bedrafted now and executed by all parties . We discourage adding the completion of this step as a condition to any Planning Board approval . d . A copy of a sealed boundary and topographic survey must be submitted with any subsequent plans . e . The alterations within the Lakeview Subdivision may require additional Planning Board action on previous approvals granted that project. 2 . Stormwater Management: a . Hydrologic Calculations : P The drainage areas provided in the report donot include off-site runoff, and It is unclear from the plans provided how much area this may include . • The drainage analysis includes tufo design points ( Design points 1 and 2) . Although off-site runoff needs to be included , the drainage boundaries for the Post-Developed condition appear to be otherwise correct. However, in the Pre- Developed condition , the drainage area to Design Point 2 is incorrect, as much of this drainage area actually appears to flow to the east, with at least some runoff flowing toward the swale behind lot 32 of the adjoining property. b . Site Layout and Grading : • Ina few areas , the site grading is not very clear. An example is the swale between lots 17 and 18 , where the .contours do not appear to tie in to existing contours . Another is the 18" culvert that crosses " New Road B". where the , invert in,and outdo not match upwith`the contours shown on the .plan . • The proposed road `grades are steep in some 'locations (on the order"of 12 % ) . As designed , • the road is directly perpendicular to the existing site contours in these areas : ` • • The septic sizing provided assumes 8% natural slope , but many of the lots exceed this slope . 203 North Aurora Street • Ithaca, New York 14850 Telephone (607) 272-6477 • Fax (607) 273-6322 • www.tgmillerpc.com • r c . Permanent Stormwater Management Practices : • • The proposed stormwater management pond does not meet the following criteria set forth in the New York State Storwmater Management Design Manual : Minimum Length to Width Ratio of 1 . 5 : 1 ( Required ) Long Flow path (design guidance) Irregular Geometry ( Design Guidance) Pond Buffer ( Required ) • The dry swale proposed does not meet state standards due to the shallow depth of material above the underdrain . This practice only treats a few lots , and a traditional grassed channel " may provide sufficient treatment. Regardless of which option is used , a "60-day" DEC review period will be required . • A more detailed long-term maintenance is required for both the pond and dry swales . d . Erosion and Sediment Control : • The plan calls for rock check dams on rock-line channels , which is unnecessary. • The construction sequence is not of sufficient detail . It is unclear when the road will be constructed relative to individual lots . • There are no ESC or grading plans for individual lots . A generic plan would typically be sufficient to cover these lots . In this case no generic plans are included , and more detail will be required due to the steep slopes of some lots (5-7 and 10- 14) . e . General Format: • Some referenced documents are currently out of date including : The 1997 "Guidelines for Erosion and Sediment Control" and TOG 5 . 1 . 10 have been replaced with a 2006 document available on DEC's web site . The "Reducing the Impacts . . . " document is also out of date . Drake Road Subdivision — Sketch Plan • 1 . Stormwater Management: a . Grading - As portrayed , the swale capturing runoff from lots 6 and 7 is immediately at the top of a very steep slope . It would be preferable to capture only rooftop and driveway runoff than to risk disturbing this slope during construction , or introducing concentrated runoff to it in the long term . b . Hydrology/ Hydraulics - We received no updated hydrologic report, so we cannot evaluate if the practice identified provides sufficient controls . c . Erosion and Sediment Control : • Provide more detail on construction sequencing . • If the houses will be developed separately, they will need a stand-alone sequence . • Will the stormwater pond be used during construction as a sediment trap , and if so when will sediment be removed? d . Permanent Stormwater Management: • Insufficient design information is available regarding retention area sizing and routing . • The contours provided suggest that the pond does not conform to the geometry guidelines and requirements set forth in the " New York State Stormwater Management Design Manual" as follows : Minimum Length to Width Ratio of 1 . 5 : 1 ( Required ) Long Flow path (design guidance) Irregular Geometry ( Design Guidance) Pond Buffer ( Required ) e . General Format : • Some referenced documents are currently out of date including : The 1997 "Guidelines for Erosion and Sediment Control" and TOG 5 . 1 . 10 have been replaced with a 2006 document available on DEC 's web site . • The " Reducing the Impacts . . . " document is also out of date . A r' Feel free to contact me with any questions . Thank you . • ' • erely, a44 ,• A. Herrick , - . E . Cc : S . Farkas D . Platt J . French G . Krogh • • • 0 o 0 D. g m 0 O o X X X X X X X X X o O 0 m 0 - "Z U V 03 U W U m t0 s o x x x a m d Q gggm X X X O O O X O X K m O C 0 C x 3 X 0 0 X X X X X X X a a 01 x x 0 0 0 0 X 0 X 0 0 0 0 - M K X K O K X K X X X NI m 0 O x ^ X X X O O O K X X O �pQa u a i` X K X X X X K X O X 8 LL j X 0 X X X O X X X X § w f�V X X X X X X K X X X m F o m = Z t x c o m 0 aJ — g - - - - W - c _ K — c _ o gg: c O w c 2 G _ m m' ✓ y m m m S .a_ 5- O a 1 m m S m m 0 m 0 — m t .�. m O W Z -1 -1 2 a 0 Q Q i ry M a m m � m w o w R �' (N n '`C n r $ R' R M M m A M a6 it