RAMANESSIN BROOK STORMWATER MODELING & POLLUTANT LOADING STUDY Monmouth County Planning Board Navesink-Swimming River Group 319(h) Grant funded through NJDEP October 26, 2005 Presented by: Jeremiah D. Bergstrom, CLA, ASLA Thomas Amidon, MS Gopi Jaligama, MS Ramanessin Brook Project Overview � Evaluate sources of fecal coliform and phosphorus � Develop a hydrologic model and watershed pollutant-loading model of the stream � Assess water quality impacts due to nonpoint sources – erosion – stormwater 1
Primary Tasks � Watershed characterization and assessment � Water quality sampling program – fecal coliform (FC) – total phosphorus (TP) – total suspended solids (TSS) � Develop a GIS-based pollutant loading model � Collect necessary data and develop a hydrologic and hydraulic model � Analyze watershed and present findings Overview of Presentation � Watershed Characterization � Field Sampling � Watershed Analyses – Glauconitic Soils Evaluation – Hydrologic and Hydraulic Modeling and Analyses – Shear Stress Analysis – Pollutant Loading Modeling and Analyses � Water Quality Results – Bacterial indicators – Phosphorus – Suspended solids � Implications and Recommendations 2
Watershed Characterization � Total Area = 6.3 square miles (4,040 acres) � Ramanessin Brook flows approximately 5 miles falling nearly 300 feet from its headwaters to its mouth at the Swimming River Reservoir � Primary water quality concerns include aquatic life, fecal coliform, and total phosphorus impairments Landuse Characterization for Ramanessin Brook Area : 6.315 sq mi. Curve Number: 76 WETLANDS AGRICULTURE 17% 18% WATER 1% BARREN LAND 1% FOREST 18% AGRICULTURE UrbanRES 28% BARREN LAND FOREST UrbanCOM UrbanRES WATER WETLANDS UrbanCOM 17% 3
2002 Aerial Photograph Soil Characteristics � Upland soils Freehold-Urban Land- – Collington Complex � Flood plain soils Humaquepts, frequently- – flooded-Manahawkin � Soils high in glauconite 0% to 40% glauconite – � Groundwater recharge rates above-average throughout the – watershed area weighted average of 10.4 – inches per year 4
Flood Plains, Wetlands and Streams � Extensive flood plain wetland areas remain nearly 1200 acres – � Flood plain approximately 250 ft wide – it expands to nearly 500 ft in – width near its mouth � Wooded wetland areas along many stream segments � Extensive downcutting of the stream bed has occurred steep banks throughout – much of the stream reach Diagnosing Sediment Impacts � Properties of glauconitic soils – high iron content – binds phosphorus – erodable clay particles – may create a sustainable habitat for bacteria � Water quality and sediment samples – better understand role of sediments as a source of NPS pollutants in stream 5
Field Sampling � Bi-weekly sampling over a 12 month period � Flow and water quality under various flow conditions � Pressure transducers installed to continuously record stream depth � Stream bed sediments and bank soils analyzed – Particle size – FC and TP Sampling Stations � RB1 North Branch @ – Crawfords Corner � RB2 West Branch @ – Longstreet Rd � RB3 Roberts Rd Bridge – � RB4 Main St Bridge – � RB5 Willow Brook Rd – Bridge � BASE Unnamed tributary – 6
Sampling Events � Stream survey – 55 detailed cross-sections � Flow and water quality sampling – Bi-weekly for one year – Flow, total phosphorus, dissolved reactive phosphorus, total suspended solids, turbidity, fecal coliform, fecal streptococcus (limited) – 5 high-flow, 6 low-flow, 13 ambient flow events � Soil sampling (May 3, 2005) – Chemical, biological, and particle size analyses Glauconitic Soils Evaluation � Determine potential for erosion of glauconitic soils within the Ramanessin Brook Watershed � Using the USLE factoring in percent glauconite, soil erodibility and slope � Identify areas with potential for eroding high amounts of glauconite into waterways independent of land use activities 7
Glauconitic Soils Evaluation Glauconitic Soils & Land Use 8
Purpose of Watershed Modeling � Better understand response of stream flows to precipitation � Provide basis for evaluating flooding potential � Better understand erosion potential under various flows � Better understand potential sources of pollutants in the stream � Evaluate impact of land use changes Modeling Approach � Hydrologic Modeling with HEC-HMS � Hydraulic Modeling for Steady State Simulations with HEC-RAS � Hydraulic Modeling for Dynamic Simulations with DAFLOW / WAMIT � Pollutant Loading Modeling using WAMIT 9
H&H Modeling Summary � Estimated volume of surface runoff from various design storms – 1, 2, 10, 100 year storms � Completed a 6 month continuous simulation to analyze real-time flows – November 3, 2004 through May 4, 2005 � Estimated the shear stress in different stream reaches for various design storms � Estimated total volumes, peak flows, total loads, and total shear stress for design storms HEC-HMS Model Delineated Watersheds and Streams � 20 Sub-Watersheds – � Defined Watershed Parameters Flow path length for estimating Time of – Concentration (Tc) Area weighted curve numbers (CN) – � CN = 76 (existing conditions) Defined Critical Storms and Precipitation � Design Storms (Shape and intensity) – Hourly precipitation data - Holmdel – Weather Station (11/3/04-5/4/05) Defined Flow Routing Parameters � Channel slope – Manning coefficients – Channel length – Calculated runoff using the SCS curve � number method (TR 55) 10
Sub Watershed Composite Curve Numbers Snyder Coefficients Area CN S Ia Sub Basin (Acres) Area Wt (Retention) (Initial Abstraction) Tp Cp R110W560 79.135 77 2.92 0.58 1.261 0.620 R130W20 584.168 72 3.80 0.76 1.974 0.620 R140W140 62.048 74 3.58 0.72 1.202 0.620 R150W150 76.699 70 4.28 0.86 1.203 0.620 R180W180 137.761 76 3.12 0.62 1.596 0.620 R240W230 108.032 74 3.59 0.72 1.211 0.620 R250W250 280.094 71 4.04 0.81 1.878 0.620 R360W320 153.916 83 2.08 0.42 1.486 0.620 R370W160 474.464 75 3.39 0.68 2.407 0.620 R380W380 174.073 83 2.09 0.42 1.753 0.620 R400W220 632.462 76 3.09 0.62 2.412 0.620 R40W570 404.970 69 4.48 0.90 1.724 0.620 R420W420 99.585 86 1.64 0.33 1.376 0.620 R430W410 154.503 80 2.46 0.49 1.425 0.620 R470W470 101.691 72 3.91 0.78 1.342 0.620 R480W450 80.691 79 2.74 0.55 1.161 0.620 R490W490 78.651 74 3.45 0.69 1.399 0.620 R510W510 141.138 83 2.05 0.41 1.714 0.620 R530W530 134.599 82 2.17 0.43 1.628 0.620 R550W550 83.200 84 1.93 0.39 1.435 0.620 Design Storm Rainfall Totals 24-HR RAINFALL TYPE III STORM (INCHES) 1-Year Storm 2.9 2-Year Storm 3.4 10-Year Storm 5.2 100-Year Storm 8.9 Monmouth County Rainfall Totals for Standard Design Storms 11
Precipitation hydrograph from Holmdel weather station = rainfall record gaps Hydraulic Model: Steady State Simulation using HEC-RAS � Initial Setup with HEC-GeoRAS � Cross section information derived from surveyed cross sections – over 50 cross sections along the approximately 5 mile stream length including 4 bridges � Performed steady state flow simulations – Peak flows from HEC-HMS used as input for design storms – Can be used to determine flood elevations and extent 12
Sample Cross Section (Upstream of RB3) Sample Cross Section (Upstream of RB3) 13
Sample Bridge / Culvert (RB4) Sample Bridge / Culvert (RB4) 14
Hydraulic Modeling: Dynamic Flows using DAFLOW / WAMIT � DA-FLOW – A one-dimensional flow model developed by USGS � Watershed Model Integration Tool (WAMIT) – a GIS-based interface to link sub-watershed flows generated by HEC-HMS with DA-FLOW – Calculates instream velocities and shear stresses � Results used to calculate depths, velocities and shear stresses at various locations in the stream under various conditions DAFLOW / WAMIT Interface 15
DAFLOW / WAMIT Results H&H Analyses � Peak Flow Calculations for each sub- watershed under 1, 2, 10, & 100 Year Storm Events � Total Volume Calculations for each sub- watershed under 1, 2, 10, & 100 Year Storm Events � Total Shear Stress for each stream reach under 1, 2, 10, & 100 Year Storm Events 16
Recommend
More recommend
