STORMWATER MANAGEMENT REPORT MEGA PALACE 5211 ROUTE 38; PENNSAUKEN, NJ 08109 PREPARED FOR: MEGA PALACE INVESTMENT, LP 5201 ROUTE 38 PENNSAUKEN, NJ 08109 PREPARED BY: CIVIL & ENVIRONMENTAL CONSULTANTS, INC. 370 EAST MAPLE AVE; SUITE 304 LANGHORNE, PA 19047 CEC PROJECT 194-266 FEBRUARY 2020 REVISED MAY 2020 MEGA PALACE STORMWATER MANAGEMENT REPORT TABLE OF CONTENTS 1.0 GENERAL PROJECT DESCRIPTION .........................................................................3 1.1 Site/Project Information .......................................................................................... 3 1.2 Owner of Record: Mega Palace Investment, LP ..................................................... 3 1.3 Existing Conditions ................................................................................................. 3 1.4 Soil Information ...................................................................................................... 4 1.5 Geologic Conditions ............................................................................................... 4 1.6 Proposed Development ........................................................................................... 5 2.0 STORMWATER MANAGEMENT.................................................................................5 2.1 Existing Stormwater Drainage ................................................................................ 5 2.1.1 Stonegate 1 ...................................................................................................5 2.1.2 Saigon Plaza .................................................................................................5 2.1.3 Mega Palace .................................................................................................5 2.1.4 Existing Outlet Pipe .....................................................................................6 2.2 Proposed Stormwater Management ........................................................................ 6 2.2.1 Conveyance ..................................................................................................7 2.2.2 Groundwater Recharge ................................................................................7 2.2.3 Stormwater Quality ......................................................................................7 2.2.4 Stormwater Quantity ....................................................................................8 2.2.5 Existing Outlet Pipe .....................................................................................9 3.0 EROSION AND SEDIMENTATION CONTROL .........................................................9 3.1 Overview ................................................................................................................. 9 3.2 Sequence of Construction ..................................................................................... 10 Civil & Environmental Consultants, Inc. -1- 194-266 May 4, 2020 MEGA PALACE STORMWATER MANAGEMENT REPORT TABLES Table 1 NOAA Rainfall Table APPENDICES Appendix A Soils Information Appendix B Pre-to-Post Peak Rate Calculations Appendix C Wet Pond Calculations Appendix D Storm Sewer Calculations Appendix E Drainage Area Boundary Maps Appendix F Off-Site Conveyance Pipe Flows Appendix G Existing Outlet Pipe Civil & Environmental Consultants, Inc. -2- 194-266 May 4, 2020 MEGA PALACE STORMWATER MANAGEMENT REPORT 1.0 GENERAL PROJECT DESCRIPTION 1.1 SITE/PROJECT INFORMATION 1.2 OWNER OF RECORD: MEGA PALACE INVESTMENT, LP 5201 Route 38 Pennsauken, NJ 08109 Parcel Information: Block 6001; Lot 73.04 Deed Book 10680, Page 1950 Property Address: 5211 Route 38 Gross Area: 3.27± Acres; (142,462± SF) Project Surveyor: Vargo Associates Surveying & Mapping PO Box 647 Franklinville, NJ 08322 Phone: 856-694-1716 Wetland Specialist: The Hyland Group 2001 US-46; Suite #310 Parsippany, NJ 07054 Phone: 973-879-6696 1.3 EXISTING CONDITIONS The parcel referenced above is a land locked parcel located immediately north of the existing Saigon Plaza. The parcel is nearly rectangular, having a minimum width of 592± feet and a depth of 229± feet. The width of the parcel faces Route 38 at an angle. In addition to Saigon Plaza to the south, the property is bound by additional commercial property to the southeast; single family residential to the northeast; Age & Income qualified apartments to the north; a former school to the northwest; and single family residence to the southwest. For the purposes of this report, the property is mostly wooded with some open meadow at the northern corner of the site. We should note that at the time of the report some of the trees had been removed. The Hyland Group investigated the property and delineated wetlands within a drainage ditch along the southern property line and a wetland within the eastern part of the site. A 50-foot transition area applies to the eastern delineated wetland. The wetland within the drainage ditch does not have a buffer. The slope of the site ranges from nearly level (0-3%) in the western half to slight (3-8%) approaching the wetland. There are some steeper slopes, which define the banks of the drainage ditch. Civil & Environmental Consultants, Inc. -3- 194-266 May 4, 2020 MEGA PALACE STORMWATER MANAGEMENT REPORT A review of the NJ-GeoWeb indicates: • A wetland in the approximate area that the Hyland Group delineated a wetland onsite. • A known contaminated property off the southern corner of the property. The only structure on-site is a storm sewer line, conveying water from the existing basin on the Age & Income Qualified property north of the property to the drainage ditch along the southern property line. 1.4 SOIL INFORMATION The soils present on this parcel are: Symbol Soil Series Name Hydrologic Group Slope HowB Howell Urban Land Complex C 0-5% USUDHB Urban Land – Udifluvents Complex Unranked 0-5% The above referenced soils have the following restrictions, which are applicable to this project: Depth to Saturation Zone: The contractor shall have a pump on site with filter bag. Filter bags shall be placed in areas not subject to erosion and installed as per the manufacture recommendations. Frost Action: Grading shall be minimized during winter months. Contractor shall utilize appropriate shoring methods at all times. 1.5 GEOLOGIC CONDITIONS This property is within the CAPE MAY FORMATION (Qcm2) (Salisbury and Knapp, 1917)--Fine-to-coarse sand, minor silt and clay; yellow, brownish-yellow, reddish-yellow, very pale brown, light-gray; minor pebble gravel. Massive to well stratified. Sand is quartz with a little glauconite and a trace of mica and feldspar. Gravel composition as in unit Qtu. As much as 40 feet thick. Unit Qcm2 (Newell and others, 1995) forms a terrace with a maximum surface elevation of about 35 feet. Fossils, pollen, and amino-acid racemization ratios in shells from this unit elsewhere in the Delaware estuary and Delaware Bay area indicate that it is an estuarine or fluvial-estuarine deposit of Sangamon age (about 125,000 years ago), when sea level was approximately 30 feet higher than at present in this region (Woolman, 1897; Newell and others, 1995; Lacovara, 1997; Wehmiller, 1997). Unit Qcm1 is an older estuarine or fluvial- estuarine deposit of uncertain age that forms a terrace with a maximum elevation of about 50 feet. A bed of black clay within Qcm1 (the "Fish House Clay" of Woolman, 1897), formerly exposed in the pit just south of Delair Junction, contained freshwater mussels, horse bones and teeth, pine and birch bark, and maple, oak, and basswood leaves (Woolman, 1897; Bogan and others, 1989). These fossils indicate that the Cape May 1 unit was deposited in a temperate, interglacial climate. Because it is at higher elevation than Sangamon-age deposits, it was probably laid down during a pre- Sangamon Civil & Environmental Consultants, Inc. -4- 194-266 May 4, 2020 MEGA PALACE STORMWATER MANAGEMENT REPORT interglacial sea-level highstand and is of early or middle Pleistocene age (Lacovara, 1997; O'Nea1 and McGeary, 2002). Salisbury and Knapp (1917) included fluvial terrace deposits within the Cape May Formation; here they are mapped separately as units Qt1 and Qtu. 1.6 PROPOSED DEVELOPMENT The purpose of this project is to construct a Multi-use Commercial building and associated parking. The proposed building will face Siagon Plaza and Route 38. Four (4) new access points will be constructed: three (3) to Saigon Plaza and one (1) to the former school property. There is no proposed connection or improvement to any of the surrounding public streets. This facility will be served by public water and sewer. Both of these will be extended from the Former School property. 2.0 STORMWATER MANAGEMENT 2.1 EXISTING STORMWATER DRAINAGE 2.1.1 Stonegate 1 An existing 24 inch storm sewer pipe is located on the Mega Palace parcel. This pipe conveys runoff from an existing basin located on the Stonegate 1 parcel. Attempts to retrieve the SWM design calculations for the basin were unsuccessful. To quantify a design flow through this existing pipe a preconstruction runoff computation was performed to determine the maximum allowable flow that would have been permitted to discharge from the existing basin. The runoff from the existing basin for the 25 year storm is projected to be 10.36 cfs. See Appendix F for the summary sheets. 2.1.2 Saigon Plaza An existing underground detention basin is located within the northern portion of the Saigon Plaza parking lot. This system was installed circa 2006. The basin outlet pipe connects to the existing