Analette Ochoa, P.E., QSD/P, ToR, WRECO

May 22, 2013

LID Treatment Case Study-Bransten Road

2

Project DescriptionConceptual Design with Three AlternativesDesign Parameters- MEP vs. C.3 Challenges

Project Description

3

Clean Watersheds for a Clean Bay (CW4CB)Industrial SiteLocation chosen to evaluate potential PCB load

reductions977 Bransten Road – “Hot Spot”

Old County Road

Industrial Road

Brans

ten

Road

San Carlos

Treatment BMP Concept

4

Both sidesUnderground

treatment/ maximize parking

At hot spots

Considered Three Treatment Alternatives

Treatment BMP Concept – Alternative 1 and 3

5

Treatment BMP Concept – Alternative 2

6

Treatment BMP Concept

7

Alternative 3 chosen for cost-effectiveness

Treatment BMP Concept

8

Watershed Map

15.6 ac

9

$$ Utilities/PotholingCost effectiveness comparison: $/sq ft of treatmentPublic meetings: Input from property owners

Treatment BMP Concept

Design Parameters

10

9 Bioretention Swales in Bulb-outs

11

Design Parameters - MEPNeed for parking vs. need for WQ improvementsRoadway watershed vs. off-siteReduced width from 8’ to 6’ to avoid gas line conflictUnderdrain vs. no underdrains18” vs. 12” deep bioretention soilTemporary vs. permanent irrigation

Special Design Parameters

12

16” deep curb - stability analysis against overturning or sliding

Impermeable liner -protection of roadway and utilitiesBulb-out Radii -

Consideration for trash/sediment accumulationIndustrial site - Truck turning radius

Irrigation Ordinance - low flow sustainable designPlanting - smaller trees due to utility conflicts

13

ChallengesUtility conflicts

Urban AreaWater MainSewerPG&E Gas

Design considerationsImpermeable linerDeeper curb on roadway sideConcerns with differential

settlement

Soils8 boringsHSG DHazardous soilsGroundwater 5.5- 7.5 ft

14

Challenges

ChallengesFlat area - Minimum

hydraulic head, no drainage system

Underdrain vs. no underdrain

Planting of trees

15

Summary of Bioretention Areas

16

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

17

Coordinate with utility companies earlyInform utilities of project goals (compaction)Obtain schedule for review/comment periodPothole Understanding planting goals with utility clearances

(overhead/underground)

Hold public meetings to get approval from adjacent property owners or companies for parking needs

QUESTIONS

18