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Home My WebLink About20210755 269 Broadway Site Plan Public Comment (10) Public Comment May 25, 2022 Project 269 Broadway Site Plan Project 20210755 RE: Hydrogeological Report by Terracon dated May 18, 2022, and CHA Comment Review Response. 1. The hydrogeological report was prepared with no new data. It indicates more borings and testing will be done for design purposes. 2. No testing has yet been done to determine soil conductivity, transmissivity, or grou ndwater velocity. The report indicates additional borings and testing are important. Due to the many complications of this project, the PB should require this information before Site Plan approval. 3. The report states the following (highlights have been added): T��Br�oad�uv��r P�o��i��is I��c��ed��prc�xirr�at�ly 1��f��t w�st c�f the fa�ult.�in�e tl��c�lut�on- enl�r�ed fr�cture� �nd s�ams �hich ��rry th��+v�t�r tc�th�fault�re ��o deepl� �e�ted, �nd that na ��r�tc��-ty�e miner�l �pring��r�vvell� h��r� ��rer�een f�und��t��he f�ult, it is unlikely that th� �rc�j��t will imp��t or�ffe�t �n� c�f the ��ci�ting��rinc��lw�ll�. In �ddition, it i�als� higl�ly unlikel�r f�r thi� r��s�c�n tl��t an� �pring v�r�t�r� v�rill be en�ount�r��d �urir�� the �dr��n�err��nt �f th� ��c�n� pil� ��I s��k�t� int�th� k��c��k. It i� of r��t�th�t� r��k��r�c�ll�ct�d fr�rr�b��ir�g� B-2 a��f��t k��l�v� The statement that the springs will unlikely be encountered is repeated in the Conclusions of the report which states "it is unlikely that the secant wall pile sockets will intercept any springs or affect the nearby "springs" (wells) in Congress Park." These statements of the impact on the springs being "unlikely or highly unlikely" is not very exact. In addition, the statement that springs won't be encountered during the drilling of the secant wall seems in conflict with historical records. The following was uncovered by the City Engineer's office. It shows the Washington and Crystal Springs on/near the site of the project. 1 - f -�+� p �� .� �,-��.t. ',� �"�r �t' �� ' � � -� �':� �y n . ��- �� a �i �� : � C��,'�►� � � T C� � '' �` �'� . �,�'� '� ri �1► � � L�' ,�a � . � .-�,� �� ,� ,,,�.�•._. '� �.�. •� .�. 9 • 7 . . , � � � �� r .,` �� , �o �� '; � '� �'�� ' . '�.� �'�� T� Additional documents discuss the two springs and list them as currently "lost". �il��l�D�,+ ��l��..�'I�,�. LJ►i1Li!!��idl��u►�a �� Q�� "V"�� Wc�r" �.Sl��i7lilt� r 11I1��"�►t��'1��'S��1C�7� ��. Washin�t�m Br�dwaY r n�ar'U�a��r��an l�st L.��a�ad 5pr�ng B �a�clw,�►y , � .... s r�. 1].,�.,�.�,AA�ncit't� If there is no certainty about what will or will not be encountered during the drilling operation, what might be the contingency plan if there is an encounter? 4. The City Engineer measured the water flow in the storm drain adjacent to 268 Broadway on May 4 as 150 to 180 gpm (220,000 to 260,000 gallons per day). The report characterizes this as coming from the dewatering system beneath the building. This is incorrect. The water comes from the French drain designed by Dente(Terracon) in 2007. Their June 27, 2007 report states "The french drain should be installed incrementally along with the wall so that groundwater does not dam up behind the wall." The documents show the french drain was placed at the groundwater elevation of 289.1, not under the building. It was not intended to lower the existing groundwater but rather to maintain the existing groundwater level outside of the cut-off walls. Doing so, it left the water conditions for the adjacent buildings unaffected. The Dente report did recommend drains be placed below the building. That water is pumped as needed through a separate pipe into the storm drain. Little to no water was observed at the time of the City Engineer's measurements. The proposed secant wall creates the same concern that the groundwater may dam up outside it. It appears the French drain concept was a good one by Dente (Terracon)for 268 Broadway. 2 Why not install a similar french drain around the secant wall? The groundwater elevations from the geotechnical report are between 289 and 292. The stormwater inverton Hamilton Street isat EIev290.22 and 290atthe doghouse. Whycan'ta similar French drain be added to the perimeter of the building at Elev 290 to 292 that gravity drains to the Hamilton Street storm system? This would be beneficial to the adjacent buildings and street utilities. 5. Going back to the water flow outside 268 Broadway, Dente (Terracon) estimated the french drain would flow at a rate of 6,000 gallons per day after construction was completed on the building. The actual flow was measured at between 220,000 to 260,000 gallons per day. The disparity between the estimated and actual flow rates questions the ability to accurately predict the groundwater flow. It also seems to further justify the need for a french drain on the 269 project. 6. The boring location plan was omitted from the Revised Geotechnical dated Feb 1, 2022. It was on the original report(see next figure) but should be added to the Revised report for historical accuracy. . � � � � � - � rr , �. � � r = T�st Braring Nv. �nc�Appr�x. L�cation�tYp.} - _ �� g_� � ` �� A��prvx. Lirr�ti��vf Prvp e� �u�Idi g s "�' • �� r .� �*.� ., � ` i �� r" -� ,••��. ;r ,�.. �. . f • . 1 � [�_� • } � ,� �, '�7 � _ ^�r .,..� •-* � �� J► � — �r � -- ••� ��f7 + �� i'i � g� �� •�! `� - f r �� + � � - �� g_�'� � � � _ .� F��m�� ,�.�. �_�,_,-_ �� _ � � ,� , Bui�ding �� -... �'_� ,r.:�• `�- .-. "�.. .'�.,�- _� � �`� ~ _ � � • � �� - .�� • �- _ .� _ . -� •. � _ _ fiiir�'-� -� � �.. . '� - � -� B-�' - '`��•,r,.- � . a „� � � �-- -- - ,.. � � � . M I �_� � � • �� - - �� •w� � r�• ��'�/ s� � '�: 7. The hydrogeology report recommends the need for additional testing and reports with those being supplied to the City. 3 The City should not be just a receiver of reports but should be an active participant in assessing the reports, recommending further testing if needed, and stopping work if unsatisfactory results are obtained. 8. The hydrogeology report states that "Proposed dewatering methods during construction will need to be submitted by the contractor selected and reviewed and approved by the Geotechnical Engineer of Record." The NYS Building Code requires a Special Inspector approved by the City and retained by the Owner. All aspects of the foundation system and dewatering should be presented in a Statement of Special Inspections with any design documents for building permit approval. Conclusions/Summary: The applicant's new technical information and the City and CHA reviews have enhanced the knowledge of the proposed project. Additional work is still recommended as noted previously before PB considers approval. The City's search for historical documents regarding the springs is a start to developing a database that could be useful for assessing future development. The PB should mandate that future projects proposed in the City provide a full geotechnical report and groundwater assessment before SEQR and PB Site Plan approval. Rega rd s, David Biggs 268 Broadway Saratoga Springs, NY 4