David Clouser & Associates

Licensed Professional Engineers and Land Surveyors

One Paradies Lane   Ñ  Suite 200

Telephone: (845) 790  - 5108

Fax: (845) 790  - 5181

E-mail: dbsea@dcaengrs.com

 

September 21, 2006

 

Mr. Herb Schech, Chairman

Town of Patterson Planning Board

P.O. Box 470

1142 Route 311

Patterson, New York 12563

 

Re: Patterson Crossing Retail Center

      State Route 311

      Town of Patterson/Kent

      DEIS Engineering Review Comments

 

Dear Chairman Schech and Planning Board Members:

 

            At the request of our client, the Croton Watershed Clean Water Coalition (CWCWC), our office has reviewed the Patterson Crossing proposed project’s Draft Environmental Impact Statement (DEIS) with regard to particular engineering issues. Specifically, we have reviewed issues regarding conformance with town zoning code requirements, stormwater impacts, erosion and sediment control issues, potential impacts to surface water and groundwater quality, sanitary sewer treatment and the effects of the proposed site alteration. 

 

Our office has received and reviewed the following materials in reference to the above-mentioned project:

 

·         “Draft Environmental Impact Statement”, (Chapters 1-9, Appendices A-Q) Dated July 27, 2006

·         “Engineering Drawings” dated last revised March 24, 2006

·         Dufresne Henry  consulting engineer’s project review correspondence, dated 01/24/06

·         Town Planner Richard Willams’ project review correspondence, dated 06/18/06

 

The following comments are offered on behalf of our client, the CWCWC, to be considered as part of the project’s SEQRA review / public hearing comment record.  As your Board will note during your review of the following information, it is apparent that the project does not comply with basic, minimum zoning criteria of the Town Zoning Code.  Substantial project modifications must be made to comply with your Town’s minimum zoning criteria, and this should be accomplished (which may alter the entire project) before any consideration of SEQRA issues.  Further, there are many apparent unanswered issues of concern regarding the potential for significant environmental impacts if the project is developed as represented in the DEIS materials.  Additionally, we have noted profound discrepancies in key stormwater modeling calculations that misrepresent the performance that may reasonably be anticipated from the stormwater management facilities as they are presently designed.  When these stormwater modeling variables are corrected, the systems as now incorporated in the development’s design will be shown to be significantly undersized and not capable of accommodating the scale of the project being proposed on this site. 

 

Accordingly, the Board may reasonably question whether the scale of the project being proposed is far beyond the “carrying capacity” of the property (i.e., the development constraints far outweigh the intensity of the development being proposed) in its considerations of this application.  As a general summary of our findings, it is apparent from our review of the DEIS documentation that no amount of good site planning and engineering design can overcome the numerous development constraints on this property – the project, as proposed, is simply substantially more development than can reasonably be accommodated on this very environmentally sensitive site.

 

 

             I.      Nonconformance with Zoning

 

As the Board is aware, minimally, the development must comply with the Town’s zoning criteria before serious consideration can be given to specific design features, provisions for utilities, traffic generation and all of the potential community impacts associated with these development details.  Unless the project can meet these minimum zoning / land use requirements, the project must be questioned with respect to whether the site setting and location are appropriate for the project being proposed.  Without the minimum zoning criteria being met, it becomes a substantial waste of planning resources to focus on design details.  Our review of the DEIS information indicates that the project fails to meet this minimum zoning compliance threshold.

 

After a review of the Town of Patterson Zoning Code, it has become evident that the site does not meet town zoning requirements.  The following lists the specific aspects of the project that do not comply with Town Zoning:

 

1.      The applicant is proposing a “Regional Retail Center” in the “I” zone, which requires a special use permit from the Zoning Board of Appeals.  All of the structures and parking in this proposed development are located within the “I” zoning district boundaries, as required by code.  However, it is important to note that the extensive 8.7 acre Sanitary Sewage Disposal System (SSTS) will be located in the southwest corner of the site which is not in the I zoning district (i.e., this parcel is in the R-4 zoning district.  As can readily be verified by the Board, according to Sections 154-26 and 154-27 of the Patterson Zoning Code, sanitary waste disposal systems serving industrial/ commercial facilities are not a permitted as either a principal use or an accessory use in any residential district (including the R-4 district).  In fact, the permitted uses listed in the code as allowed uses in residential districts are very specific and very restrictive to maintain a quiet, aesthetic residential character and setting and do not permit any uses in any way related to commercial/industrial activities.  Clearly, the R-4 residential zoning district was purposefully intended for residential use, and not for an expansive (8.7 acre) area for the disposal of wastewater  generated by a large industrial / commercial facility.  The Applicant therefore must relocate the septic system to an area on the site zoned for that use (i.e., the “I” zone) or be able to obtain a use variance from the Zoning Board of Appeals, prior to any serious consideration of the viability of this development proposal.  As the Board is aware, the standards that must be met to obtain a use variance are quite rigorous, and would seem particularly so in this instance due to the clear residential compatibility criteria stated in the residential district zoning specifications.

 

2.      As previously mentioned, the proposed “Regional Retail Center” requires a special use permit to be issued by the Zoning Board of Appeals.  Section 154-111 of the Patterson Zoning Code lists the specific conditions that must be met (Conditions A through E), should the special use permit be granted for Regional Retail Center. Section 154-111 (B) states “The minimum setback of all buildings, structures, parking areas and access drives shall be 65 feet”.  As the Board will note, the site plan does not conform to this requirement in several areas of the development proposal.  As an example of this noncompliance, the first 1000 feet of the access drive (extending from State Route 311 to Station 10+00) is located less than 65 feet from the property line – through one 100 foot segment of this access road, this road is located within 15 feet of the property boundary.  This aspect to project layout does not meet Town Zoning Code, specifically the requirements of the Special Use Permit in Section 154-111.  The plan must be revised to meet town code or the applicant must seek an area variance from the Zoning Board of Appeals, prior to any serious consideration of the viability of this development proposal.

 

3.      Additionally, Section 154-111 (B) also states “Sixty-five (65) feet from any rear or side property line shall be maintained as a vegetative buffer, and shall not contain any surface or subsurface improvements including waste disposal system or utility lines.”  According to the proposed site plan, significant improvements are proposed within this 65 feet wide required vegetative buffer area along both the side and rear property lines.  Since the property has frontage and is proposing access from State Route 311, the property line along Route 311 would customarily be considered the “front property line” of the development parcel.   Therefore, all other property lines must be considered “side” or “rear” property lines with the 65-foot setback applying to these property boundary lines, as referenced above.   According to the information shown on the proposed site plans, significant improvements are proposed within 65 feet of the property line along the eastern, southern and western boundaries where a vegetative buffer is required to be maintained.  Specifically, Stormwater Detention Ponds, 1.1, 1.2, 1.3, and 1.4 (as well as the pond access drive) are all located within 65 feet of the eastern property line.  Additionally, extensive grading, the proposed wastewater disposal system and access drives will also be located within 65 feet of the southern and western property lines.  Access drives, detention ponds, wastewater disposal systems and massive embankments/excavations (i.e., in excess of 40 feet deep rock cuts) certainly must be considered “surface improvements” and, according to clear provisions in the Town Zoning Code, may not be located within 65 feet of any side or rear lot line, per the zoning code.  This is yet another aspect to the project layout proposal that does not meet Town Zoning Code, specifically the requirements of the Special Use Permit.  Accordingly, the project plans must be revised to meet town zoning code minimum requirements or the applicant must seek a variance from the Zoning Board of Appeals, prior to any serious consideration of the viability of this development proposal.

 

4.      With regard to impervious surfaces, Section 154-111 (C) states “All other dimensional requirements of the particular district are conformed to, except that total area of all impervious surfaces shall not exceed 50% of the total lot area.”  The Special Use Permit for a Regional Retail Center is allowed only in the “I” zoning district, therefore, this portion of the Town’s Code applies only to that portion of the project that lies within the I zoning district.  Therefore, the applicant must show that 50% or less of the development’s total area in the I district is impervious.  Our office did not perform the precise calculation to determine compliance with this section of the zoning code because it is visually apparent when reviewing the development’s plans that the proposed layout does not meet this requirement.  The total area of impervious surfaces must be significantly reduced to achieve compliance with this section of the zoning code.  This required revision will undoubtedly result in a significant reduction in the project’s scope and scale.

 

 

          II.      TMDL Watershed Requirements

 

As the Board is aware, the proposed project is located within two (2) of the New York City Reservoir drainage basins.  A portion of the site drains to the Middle Branch Reservoir and part of the site drains to the East Branch Reservoir.  Each of these drainage basins are “Phosphorus Restricted Areas” as identified in the TMDL (Total Maximum Daily Load) requirement per federal US EPA program conditions as administered by the NYSDEC.  The Middle Branch and East Branch Reservoirs each drain to the Croton Falls Reservoir, which is also classified as “Phosphorus Restricted”.  The specific water quality criteria for development in these watershed areas are regulated by the New York City Department of Environmental Protection (NYCDEP) and the New York State Department of Environmental Conservation (NYSDEC).  The area’s TMDL Program was established as a joint effort with the US EPA as mandated by Section 303(d) of the Clean Water Act of 1977.

 

As the Board is aware, the East Branch Reservoir, Middle Branch Reservoir and Croton Falls Reservoir do not meet the NYS phosphorus guidance values (as determined by the NYCDEP and the NYSDEC) and action must be taken to improve the quality of this New York City drinking water supply.  Phosphorus concentrations are over the required maximum levels in the East Branch, Middle Branch and Croton Falls Reservoirs and therefore pollutant loadings from newly developed sites are very strictly regulated so that the water quality will not degrade further, with the long term objective of improvement in this respect for these specific watershed areas.

 

Wastewater treatment plants within the Middle Branch watershed have been targeted as point sources for excess phosphorus loading and, consequently, many wastewater plants are scheduled for or have undergone extensive treatment unit upgrades in an effort to reduce their phosphorus output.  However, the NYCDEP clearly concluded in their report entitled “Proposed Phase II Phosphorus TMDL Calculations for Middle Branch Reservoir” (March 1999) that the upgrade of wastewater treatment plants can only partially reduce the existing excessive phosphorus load in the drinking water supply reservoirs.  According to the latest NYCDEP TMDL report, non-point sources such as urban stormwater runoff are the other major contributors to the phosphorus loads within the reservoir. Very importantly, programs and measures must be implemented within the watersheds to reduce the pollutant loading from both wastewater treatment and urban stormwater runoff sources. 

 

With that said, the proposed project involving the construction of vast areas of impervious surfaces and massive land disturbance in the Middle Branch Reservoir and East Branch Reservoir watershed is a major concern, requiring substantial and complex mitigation methods to minimize this recognized significant adverse impact.  A review of the DEIS information for this project does not reveal that these concerns that affect one of the world’s largest water supplies have been appropriately addressed.

 

As summarized on Pages 4.5-6 through 4.5-9 of the DEIS, the phosphorus loading to the Middle Branch Reservoir, East Branch Reservoir and the entire Croton Falls Reservoir watershed must be reduced to meet NYS phosphorus values.  According to the TMDL report prepared jointly by the NYCDEP, the NYSDEC and the US EPA titled “Nonpoint Source Implementation of the Phase II TMDL’s,” (April 2001), phosphorus load reductions in the Middle Branch and East Branch Watersheds are required to meet water quality objectives within the Middle Branch, East Branch and Croton Falls Reservoir.  The total “Wasteload Allocation” (WLA - the contaminant load allotted by the TMDL for wastewater treatment plant discharges) is currently below the requirement as per the TMDL report.  However, the Phosphorus load still exceeds the TMDL loading limits.  Therefore, the reduction in phosphorus must come from non-point sources such as urban runoff, as well as the increasingly more strict treatment limits imposed on wastewater treatment facilities.  These documents clearly require that the phosphorus load must be reduced in this specific project area to meet water quality standards outlined in the TMDL.  Maintaining the pre-development phosphorus loading levels at this location is no longer an option.

 

As your Board is aware, the project proposes the conversion of large areas of undeveloped forest to urban areas.  As previously stated, urban areas are identified as the “…. principal phosphorus sources” in the Middle Branch and East Branch watershed.  After our office’s review of the project’s DEIS information (and as supported in our comments in Section IV. (1)), it is most probable that the project will result in an actual significant increase in the phosphorus loading to the water supply reservoirs instead of reducing this pollutant load.  Therefore this proposal does not meet the minimum TMDL requirements established by the NYCDEP and NYSDEC.  The project must therefore be redesigned to meet these TMDL Phosphorus reduction requirements. 

 

 

       III.      Stormwater SPDES Permit and the Required SWPPP

 

The NYCDEP and the NYSDEC each require the implementation of a Stormwater Pollution Prevention Plan (SWPPP) for the proposed construction activity.  However, the requirements of the SWPPP differ for each agency. 

 

The NYCDEP “Rules and Regulations for the Protection from Contamination, Degradation and Pollution of the New York City Water Supply and Its Sources” (Last revised June 30, 2002), requires the implementation of the previous SPDES General Permit GP 93-06.  However, the more recent NYSDEC Phase II Stormwater regulations require the implementation of the current Stormwater SPDES permit GP 02-01. 

 

For this project, both permits must be satisfied to comply with current regulations.  The NYCDEP will review the project design to insure that their requirements have been met and the NYSDEC is required to also review the stormwater design in compliance with the SPDES requirement for projects located in a TMDL area.  In cases where the requirements within the regulations “overlap”, the worst case, most stringent standard must be used, as verified with regulatory review staff members at both the NYSDEC and the NYCDEP.   As follows in this evaluation of the DEIS documentation, instances of non-compliance with both agencies’ standards are apparent in our review of the stormwater management facilities’ design.

 

 

       IV.      SWPPP Comments

 

Our comments specific to the Patterson Crossing Stormwater Pollution Prevention Plan (Appendix F of the DEIS) are as follows:

 

1.      Section 2.0 - Some of the pollutant loading rates for specific land uses utilized in the project analysis, taken from the Terrene Institute’s publication “Fundamentals of Urban Runoff Management” are inaccurate and do not represent variables that should be used in the pollutant loading calculations.                                                                                  

 

Amended pollutant loading rates for Phosphorus specific to the project area are used by the NYCDEP in TMDL reports, as in “TMDL Calculations for the Middle Branch Reservoir”, “Table 4.1 – Land Use Export Coefficients for the Middle Branch Reservoir”.  These more recent pollutant loading rates have been validated through years of field monitoring throughout the watershed basin area and are specifically valid for use in the pollutant loading calculations for this project.  The pollutant loading rates are commonly used by the NYCDEP throughout their extensive researching and reporting of the Croton Falls Reservoir watershed as well as many other reservoirs east of the Hudson River.

 

The phosphorus pollutant loading values utilized in the above referenced TMDL Reports for undeveloped forest is significantly less than what was used in the project analysis.  The following table summarizes the different pollutant loading values and provides an example of the disparity between the DEIS values that are being used in the Applicant’s documentation that is purported to model the pollutant loading and removal rates for this project:

 

Phosphorus Loading Rates

Land Cover	Terrene Institute Document Rates (used in the DEIS) (lbs/acre-yr)	NYCDEP TMDL Report Rates (lbs/acre-yr) [current standard]
Undeveloped forest	0.1	0.045

 

 

 

      As shown in the above table, the pre-development pollutant loading estimates have been overstated in the DEIS analysis information by a multiplier of approximately 2.2.  The analysis should be revised to use the proper loading rates, and subsequently the stormwater quality treatment design must be revised to accommodate these significantly more stringent standards.  The outcome of using the proper variables will require increased treatment facilities and may result in a substantial reduction in the project’s scale --- or perhaps indicate that the present proposal is not an appropriate use for this specific site.

 

     Additionally, the stormwater analysis utilizes the pollutant loading rates taken from the  Terrene Institute’s publication “Fundamentals of Urban Runoff Management” for developed conditions such as for commercial, residential and impervious ground cover conditions.  The values taken from this document are not appropriate for this application. 

 

As noted on page 38 of the Terrene Institute document “The author drew values from the general literature and data collected in the Pacific Northwest”.  With regard to the pollutant loading rate table also on page 38 of the document, it later states “This table should be as discriminately used as others, especially since most pollutants are generally lower in Pacific Northwest runoff than elsewhere.”   Expecting that site conditions are similar to those in the Pacific Northwest is unreasonable, and therefore more site specific factors must be used to provide a representative pollutant loading model.  As a minimum, modeling should utilize accepted pollutant loading factors that have been developed for use in New York State.

 

The document that is typically referenced and utilized for these calculations in New

York State is NYSDEC’s publication “Reducing the Impacts of Stormwater Runoff from New Development” (Reducing the Impacts).  The values contained in this document are specific to New York State and are commonly used in this area.

 

    The values contained in the Terrene Institute document are significantly less than what is utilized in NYSDEC’s “Reducing the Impacts” document.  The following table summarizes the different phosphorus loading values for the site and provides an example of the disparity between the DEIS values that are being used in the Applicant’s documentation that is purported to model the pollutant loading and removal rates for this project:

 

Phosphorus Loading Rates

Land Cover	Terrene Institute Document Rate (used in the DEIS) (lbs/acre-yr)	NYSDEC “Reducing the Impacts” Rate (lbs/acre-yr)
Commercial	0.71	1.5

 

 

     As shown in the above table, the pre-development pollutant loading estimates have been understated by a multiplier approximately 2.1.  The analysis should be revised to use the proper loading rates, and then the stormwater quality treatment design must be revised to accommodate these significantly more stringent standards. Using these revised loading rates will clearly indicate that the current project design does not even remotely provide the water quality treatment that is required to meet the more stringent pollutant values for pre-development conditions, let alone providing for a required reduction in post-development pollutant loading transport from the site.

 

     To summarize this phosphorus loading rate modeling issue, a careful review of the DEIS information reveals that the pre-development pollutant loading is overstated and the post-development pollutant loading that will be created by this project is understated.  This misrepresentation in the modeling data results in a grossly inaccurate estimation of pollutant loading impacts for this proposed development.  The project, as designed, will result in potentially large increases in phosphorus loading to each reservoir.  Accordingly, this project design does not conform to the TMDL requirements set forth by the NYCDEP and the NYSDEC with regard to phosphorus.

 

    It should also be noted that other pollutants have also been underestimated in the post-development loading calculations such as Total Nitrogen (TN), Total Suspended Solids (TSS) and Biological Oxygen Demand (BOD).  The pollutant loading calculations for each of these pollutants also must be revised, properly utilizing the pollutant loading rates taken from the “Reducing the Impacts” document.

 

2.      For the post-development runoff calculations, the analysis utilizes a “general” CN runoff value for the commercial development.  This “general” CN value assumes a certain percentage of the site will be impervious as well as a percentage of grassed or landscaped areas.  It is a simple and common place task to determine the “actual” areas of impervious and grassed surfaces, which would provide a significantly more accurate representation of the actual ground cover conditions and post-development drainage.  This simple calculation should be completed by the Applicant for a project of this scope and scale.  The post development runoff calculations should be revised to reflect the more accurate CN values.  It should also be noted that this office conducted preliminary calculations to determine what effect this change would have on the analysis.  Our findings indicate that the post-development runoff quantities have been underestimated due to the Applicant’s selection of the “general” CN values that were used.

 

 

          V.      Sanitary Sewer Treatment

 

As shown on the project plans, the Applicant is proposing a Subsurface Sewage Treatment System (SSTS) in the southwestern corner of the site to capture and treat the sanitary effluent from the proposed development.  The Applicant has calculated a design flow of 10,740 gallons per day (gpd) and has sized the SSTS to handle this flow.  The Applicant has utilized “custom” values for calculating the design flow based upon the historical usage of each proposed tenant.  However, the calculation should be based upon NYSDEC’s Design Standards publication that would be accepted by the permitting agency.

 

Utilizing the proper NYSDEC document for the calculation, the flow rate is calculated to be approximately 35,000 gallons per day or 3.3 times the flow calculated by the Applicant.  As mentioned in Dufresne Henry review correspondence dated 01/24/06, “Because there is always the chance for a change in tenant(s), in our view the estimated design hydraulic loading rates should be based on NYSDEC standards…”.  It is our opinion, as well as the Town Engineer’s opinion that the flow rate should be based upon NYSDEC standards, and the wastewater usage should therefore be recalculated for use in evaluating the project’s potential impact.  As mentioned by the Town Engineer, the current tenants may not always be present and future tenants may have additional demands on sewer services, resulting in an inadequately sized sanitary disposal system. 

 

Additionally, based on the information provided in the DEIS, no design has been completed for the SSTS.  The design of the system is an integral part of the environmental review of this project and should be completed at this time.  As the Board is aware, the system must also incorporate pretreatment (for phosphorus removal) prior to disposal in a subsurface system.  There is no design information for this required component of the wastewater disposal system that is being proposed for the development.  The plans portray a conceptual “black box” approach to the planning of this component – little more than an arrow pointing to where the system would be generally located is provided for review, without any of the necessary detail that could confirm or deny its feasibility.  The DEIS wastewater report narrative refers to groundwater modeling uncertainties and concern for lateral leaching of untreated sewage, without providing tentative feasible solutions to these concerns that their consultants have raised.  Significantly more detail for this critical development component is needed before impacts can be considered. 

 

The preliminary design of the system and a detailed description of its necessary components would allow the Board to more properly determine whether the system complies with agency minimum standards, fits on the site area indicated on the plans (i.e., would a system that is required to be 3.3 times the system described in the DEIS – with its required reserve area – fit in the area planned for this use?), what the extent of disturbance is, and what impacts it may have on nearby groundwater and surface water resources.  All of these questions must be accurately answered by the Applicant as an essential for the Board’s use in evaluating the potential impacts, the reasonableness of the project proposal’s scale and the feasibility of the development’s proposal being accommodated by the site’s sensitive setting. 

 

 

       VI.      General Comments / Conclusion

 

The following provides additional general planning comments on the information reviewed in the DEIS materials:

 

1.      Site / Steep Slope Alteration - With regard to the proposed construction on steep slope areas, the long-term effects of the disturbance of steep slopes are known to result in:

 

·         A loss of topsoil

·         An increase in soil erosion

·         Siltation in streams and wetlands

·         The alteration of drainage patterns

·         The degradation of the quality of surface water

·         The potential for contamination of water supplies

·         Slope failures

·         Alteration of scenic views

·         Destruction of potentially significant habitat

·         Threats to personal safety

 

The road and site construction design as shown on the grading plans would require extensive removal of soil, bedrock and woodlands.  There are locations on the grading plan that call for more than 40 feet of excavation and 30 feet of embankment.  Similarly, what consideration has been given to the substantial alteration of the local groundwater table with such an extensive earthmoving site alteration?  These examples serve as indicators of the massive site alteration that is required to accommodate the development that is proposed by this present design.  This land would be irreversibly altered by this scale of proposed site transformation and requires a substantial portion of the construction to take place on sensitive steep slope areas throughout the site.  The potential for serious impacts that might result from this type of site modification merits considerably more investigation than has been presented in the DEIS materials. 

 

2.      Stream Alteration - Sheet SP-3.1 of the Engineering Drawings indicates a DEP regulated water course extending from Concord Road to NYS Route 311, and further discharging into the Middle Branch of the Croton River.  As shown on the plan, approximately 1,000 horizontal feet of this watercourse will be destroyed by the proposed development.  Much of the watercourse will be filled in and piped underground, and large detention basins are proposed to be placed directly on top of the watercourse. 

 

The Board should consider the feasibility of construction and realignment of this watercourse with regard to requiring design details design that would be nprerequisite to obtain the proper NYCDEP permits for this proposal in addition and coincident with considering the environmental impact associated with the destruction of such a large portion of the existing watercourse.  It may also be noted that the watercourse may be additionally regulated by the Town of Kent and/or the Army Corps of Engineers.

 

It is our opinion that substantial changes to the project design are necessary to bring the project in compliance with current stormwater regulations and town zoning code.  Issues such as revised pollutant loading rates (see section IV., SWPPP, Comment #1) and non-conformance with bulk zoning requirements could substantially change the layout, scope, scale and direction of the project.  Further, significantly more detail is required to adequately describe the potential project impacts and to be able to develop workable mitigation measures.  This additional information will also then accurately portray the scale and scope of a development that the site can accommodate without unduly destroying its natural features which contribute to the community’s value and character.

 

Thank you for providing us with the opportunity to comment on this project.  We look forward to our involvement in the project as the plans develop and we receive additional design detail.  Please feel free to call with any questions or comments.

 

 

                                                                                    Sincerely,

                                                                                    David Clouser & Associates

 

 

 

                                                                                    David B. Clouser, PE, LS

                                                                                    NYS Professional Engineer No. 069334

 

 

cc:        Dr. Marian Rose, Croton Watershed Clean Water Coalition

            Mr. James Bacon, Esq.