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LID TREATMENT CASE STUDY BRANSTEN ROAD, SAN CARLOS. Analette Ochoa, P.E., QSD/P, ToR, WRECO May 22, 2013. LID Treatment Case Study- Bransten Road. Project Description Conceptual Design with Three Alternatives Design Parameters- MEP vs. C.3 Challenges. Project Description.
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LID TREATMENT CASE STUDY BRANSTEN ROAD, SAN CARLOS Analette Ochoa, P.E., QSD/P, ToR, WRECO May 22, 2013
LID Treatment Case Study-Bransten Road • Project Description • Conceptual Design with Three Alternatives • Design Parameters- MEP vs. C.3 • Challenges
Project Description • Clean Watersheds for a Clean Bay (CW4CB) • Industrial Site • Location chosen to evaluate potential PCB load reductions • 977 Bransten Road – “Hot Spot” San Carlos Industrial Road Bransten Road Old County Road
Treatment BMP Concept • Considered Three Treatment Alternatives • Both sides • Underground treatment/ maximize parking • At hot spots
Treatment BMP Concept • Alternative 3 chosen for cost-effectiveness
Treatment BMP Concept • Watershed Map 15.6 ac
Treatment BMP Concept • $$ Utilities/Potholing • Cost effectiveness comparison: $/sq ft of treatment • Public meetings: Input from property owners
Design Parameters • 9 Bioretention Swales in Bulb-outs
Design Parameters - MEP • Need for parking vs. need for WQ improvements • Roadway watershed vs. off-site • Reduced width from 8’ to 6’ to avoid gas line conflict • Underdrain vs. no underdrains • 18” vs. 12” deep bioretention soil • Temporary vs. permanent irrigation
Special Design Parameters • 16” deep curb - stability analysis against overturning or sliding • Impermeable liner -protection of roadway and utilities • Bulb-out Radii - • Consideration for trash/sediment accumulation • Industrial site - Truck turning radius • Irrigation Ordinance - low flow sustainable design • Planting - smaller trees due to utility conflicts
Challenges • Utility conflicts • Urban Area • Water Main • Sewer • PG&E Gas • Design considerations • Impermeable liner • Deeper curb on roadway side • Concerns with differential settlement
Challenges • Soils • 8 borings • HSG D • Hazardous soils • Groundwater 5.5- 7.5 ft
Challenges • Flat area - Minimum hydraulic head, no drainage system • Underdrain vs. no underdrain • Planting of trees
Summary of Bioretention Areas • Conceptual: 43 parking spaces and 6,920 sq ft of bioretention area, and 3.57 ac (155,700 sq ft) of treatment • Final: 40 parking spaces and 4,540 sq ft of bioretention area, and max 2.61 ac (113,491 sq ft) of treatment
Bransten Road - Lessons Learned • Coordinate with utility companies early • Inform utilities of project goals (compaction) • Obtain schedule for review/comment period • Pothole • Understanding planting goals with utility clearances (overhead/underground) • Hold public meetings to get approval from adjacent property owners or companies for parking needs