1. Using Groundwater and Surface Water Models for the Marcus Hook Refinery CE 394K.2 Surface Water Hydrology Presented by Julie Kim April 29, 1999

2. Study Area Marcus Hook Refinery, Pennsylvania Lube Area, southwestern part of the facility Marcus Hook Creek (MHC)

3. Objectives To incorporate results from GW model into SW model To calculate GW target level (C GW ) so concentrations in SW are not above applicable SWQS (C STD ) in MHC To compare SW model predictions for stream flow with actual stream gauging results from USGS

4. Data Sources Act 2 requirements for diffuse GW modeling and mixing calculations (PADEP) C STD : Water quality criteria for eight COCs (PADEP) Historical daily streamflows for PA (USGS)USGS GW, SW, and WW flows from A. Romanek’s GW and SW modelsGW, SW, and WW flows from A. Romanek’s GW and SW models Max concentrations of COCs from spatial analysisMax concentrations of COCs from spatial analysis

5. Methodology Simple mass balance according to Act 2 C GW = C STD * Q SW / 2q where C GW = target level GW concentration C STD = SWQ criteria Q SW = Q harmonic for carcinogens or 7 Q 10 for non carcinogens 2q = GW flow from both sides of MHC

6. Methodology No water data for MHC –Use 66-years of historical daily flow values for Chester Creek (CC) located in the same basin (Lower Delaware) –Estimate streamflows for MHC by using simple drainage area ratio Q MHC = Q CC * A MHC / A CC Calculate Q harmonic for carcinogens Harmonic mean flow = Total number of samples Sum of the reciprocal of flow

7. Methodology Use frequency analysis to calculate 7 Q 10 for non carcinogens –Calculate mean of flows of 7 consecutive days for all data –Calculate minimum flow during a 1-year period for all flows –Sort minimum flows in descending order and rank –Use Gringorten’s formula to calculate exceedance probability (b=0.44) –Calculate return period – 7 Q 10 corresponds to the minimum flow with a 10- year return period

8. Results

9. Results Benzene measured in the Lube Area was above the target GW concentration –Additional analyses should be conducted Measured peak concentrations of other COCs were below C GW –Likely that no further action is warranted Total Q harmonic = 8.76 cfs Total 7 Q 10 = 7.51 cfs –USGS-based flow is close to SW model’s regional flow of 7.7 cfs

10. Future Work Conduct additional analyses for COCs whose concentrations were above C GW –Fate and transport modeling using GW concentrations other than maximum concentrations –More sophisticated GW-SW interaction models