Green Street Challenges and Design Considerations. Watershed Revegetation Program Bureau of Environmental Services

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1 Green Street Challenges and Design Considerations Watershed Revegetation Program Bureau of Environmental Services Jeremy Person, PLA, LEED AP March 2017

2 Presentation Outline Background Challenges and Considerations Summary Questions Environmental Services l Green Street Challenges and Design Considerations 2

3 Background Environmental Services l Green Street Challenges and Design Considerations 3

4 Watershed Revegetation Program Wastewater Group Collection System Watershed Revegetation Program Natural Area Restoration Stormwater Facility Management Design and Plan Review Facility Inspection Planting Contractor Management Maintenance Irrigation Tree Pruning Environmental Services l Green Street Challenges and Design Considerations 4

5 Adopted Bureau Level of Service (LOS) CATEGORY (Good Effort) Vegetation Plants are mostly healthy Small quantities of weeds At least 75% plant survival Litter Small quantities of litter present Soils Occasional bare spots Erosion? Function Checkdam condition? Inlets are open no less than 50% of time Maintenance Effort WRP staff inspect a minimum of 2 times/year Maintenance crews visit sites 3-4 times/year Dead plants are selectively replaced Checkdams are selectively repaired/rebuilt Environmental Services l Green Street Challenges and Design Considerations 5

6 Level of Service Maintenance Activities Routine (~3-4/year) Inlet cleaning and sediment removal Leaf and trash removal Weeding Periodic (as needed) Tree and shrub pruning Irrigation Environmental Services l Green Street Challenges and Design Considerations 6

7 Level of Service Repair Activities Replanting Plant coverage or health below service level Structural Damage Chipped/cracked curbs Broken check dams, etc. Environmental Services l Green Street Challenges and Design Considerations 7

8 Pass INLETS VEGETATION COVER & HEALTH SEDIMENT Fail Environmental Services l Green Street Challenges and Design Considerations 8

9 Challenges and Design Considerations Why is this important? 1. Provide lessons learned from field observations and maintenance history - Facility Design - Facility Siting 2. Improve feedback loop between design and maintenance Environmental Services l Green Street Challenges and Design Considerations 9

10 Challenges and Design Considerations Topics Covered Planters and Swales Inlets Splash Pads Forebays Step-Out Zones Check Dams Soils Rock Galleries Environmental Services l Green Street Challenges and Design Considerations 10

11 Planters and Swales Environmental Services l Green Street Challenges and Design Considerations 11

12 Planters and Swales - Challenges Design type affects plant choices, plant health and maintenance costs. Swale Planter Environmental Services l Green Street Challenges and Design Considerations 12

13 Planters and Swales Challenges Swales may cost less to build, but more costly to maintain. Zone A Treatment area Zone B Irrigation Zone A Weed Intrusion Pedestrian Damage Zone B Environmental Services l Green Street Challenges and Design Considerations 13

14 Planters and Swales Considerations Advantages of planters Zone A only Plant installation simpler Less weed intrusion Flood irrigation Fewer external impacts Typical planter Environmental Services l Green Street Challenges and Design Considerations 14

15 Inlets Environmental Services l Green Street Challenges and Design Considerations 15

16 Inlets Challenges Must allow water to enter facility Will clog must be easy to clean Allow sediment and leaf debris to enter and be detained Trenches further complicate cleaning Environmental Services l Green Street Challenges and Design Considerations 16

17 Inlets Considerations Wide openings without obstructions work best Easy to clean Bars hard to clean Environmental Services l Green Street Challenges and Design Considerations 17

18 Inlets Considerations Trenches longer than an arms-reach require specialized tools Narrow facilities & long trenches necessitate working in the street Environmental Services l Green Street Challenges and Design Considerations 18

19 Inlets Considerations Grates should be removable Tamper-resistant vs. hex-head bolts Traffic Rated Environmental Services l Green Street Challenges and Design Considerations 19

20 Inlets Considerations Inlet opening size is very important Environmental Services l Green Street Challenges and Design Considerations 20

21 Splash Pads Environmental Services l Green Street Challenges and Design Considerations 21

22 Splash Pads Challenges Must be cleaned quickly Need to be set level with soil (+/- 1 ) Right size for the facility Angle makes cleaning difficult Environmental Services l Green Street Challenges and Design Considerations 22

23 Splash Pads Considerations Rock is time consuming to clean Concrete works best Set the pad flush with the soil to reduce erosion Environmental Services l Green Street Challenges and Design Considerations 23

24 Splash Pads Considerations Eliminate dead space Hard for plants to grow in <18 between pad and wall Extend pad to wall Easy to clean with no dead space Environmental Services l Green Street Challenges and Design Considerations 24

25 Forebays Environmental Services l Green Street Challenges and Design Considerations 25

26 Forebays Challenges Situational Need to drain no standing water Accessible and easy to clean (concrete bottoms) Environmental Services l Green Street Challenges and Design Considerations 26

27 Forebays Considerations Use on high-traffic streets or where there are sediment concerns No forebay Typical forebay sediment load Environmental Services l Green Street Challenges and Design Considerations 27

28 Forebays Considerations Weep holes clog Vertical slots preferred 1-3 wide Multiple slots Multiple slots are best Correct slot Slot not deep enough Environmental Services l Green Street Challenges and Design Considerations 28

29 Step-out Zone Environmental Services l Green Street Challenges and Design Considerations 29

30 Step-out Zones Challenges If you build it, people will walk there Protect people Protect the City s infrastructure investment Needs to be durable and reduce maintenance Neighbors build retrofit Potential trip hazard Environmental Services l Green Street Challenges and Design Considerations 30

31 Step-out Zones Lessons Learned Rock step-out zones subside, more maintenance 12 Concrete step-out more durable and low maintenance Concrete is low maintenance Rock subsides over time Environmental Services l Green Street Challenges and Design Considerations 31

32 Check Dams Environmental Services l Green Street Challenges and Design Considerations 32

33 Check Dams Challenges Multiple options. One size does not fit all. Make the solution fit the problem Need to consider lifecycle costs Materials used: clay, rock, wood, concrete, plastic, metal Environmental Services l Green Street Challenges and Design Considerations 33

34 Check Dams Considerations Clay core not durable Clay washes out Dam gets trampled or settles Rock dams do not detain water effectively Rocks don t stay in place Environmental Services l Green Street Challenges and Design Considerations 34

35 Check Dams Considerations Concrete dams are durable and lowmaintenance Makes the most sense where there is a sidewalk wall to connect to Static material; cannot be easily changed Environmental Services l Green Street Challenges and Design Considerations 35

36 Check Dams Considerations Notches are useful but can cause erosion Most important to get the height of the dam correct Elevation must be tied to other facility elements Environmental Services l Green Street Challenges and Design Considerations 36

37 Check Dams Considerations Wood dams best for retrofits, swales, challenging situations Have used Douglas Fir, Cedar, Juniper Juniper is expected to last the longest Limited sizes Chemically treated wood not permitted Susceptible to damage Rot beginning to form Environmental Services l Green Street Challenges and Design Considerations 37

38 Check Dams Considerations Wood is a dynamic material and can easily be altered Gaps at the ends are problematic Wood must be cut to fit Sealant may be used Environmental Services l Green Street Challenges and Design Considerations 38

39 Soils Environmental Services l Green Street Challenges and Design Considerations 39

40 Soils Challenges Filters storm water and sustains plant life Must infiltrate rapidly enough to get water off the street Current BES req. 40% compost 50%-60% sand <10% fines (200 sieve) Environmental Services l Green Street Challenges and Design Considerations 40

41 Soils - Considerations High-sand soil mixes greatly restrict plant longevity Uniform soil mixes retain less water in the summer Environmental Services l Green Street Challenges and Design Considerations 41

42 Soils - Considerations Weed seeds can be imported with the soil Compost breaks down over time and can export phosphorus Environmental Services l Green Street Challenges and Design Considerations 42

43 Rock Galleries 3 Filter Layer 18 Rock Storage Layer Environmental Services l Green Street Challenges and Design Considerations 43

44 Rock Galleries - Challenges Drought-related stress observed in plants in facilities with rock galleries Rock Galleries are useful tools, but should not be an assumed part of the facility Environmental Services l Green Street Challenges and Design Considerations 44

45 Rock Galleries Considerations Hydraulic Conductivity (K) Ratio at which fluids, such as rain water, move through soil, rock, plant roots, etc. Higher K means less water suspended in soil and accessible to plant roots Environmental Services l Green Street Challenges and Design Considerations 45

46 Rock Galleries Considerations Rock Galleries may be contributing to declining plant health water drains quickly through the soil (high K) and collects at the bottom of the facility Rock galleries may prevent roots from accessing this water Environmental Services l Green Street Challenges and Design Considerations 46

47 Summary Environmental Services l Green Street Challenges and Design Considerations 47

48 Recommendations Planters and Swales Planters are preferred for ease of maintenance, less foot traffic, less structural issues Upland planting areas (Zone B) should be minimized Step-out zones should be added next to on-street parking Environmental Services l Green Street Challenges and Design Considerations 48

49 Recommendations Inlets Wide openings with no obstructions Trenches Must accommodate tools: 12 wide and 4-5 long Removable grates with tamper resistant bolts Environmental Services l Green Street Challenges and Design Considerations 49

50 Recommendations Splash Pads Concrete, not rock Set flush with soil If the plantable space behind the pad is less than 18 extend the pad to the wall Environmental Services l Green Street Challenges and Design Considerations 50

51 Recommendations Forebays Best used on busy, heavily traffic streets Larger is better Use slots for drainage Slots should be 1-3 wide Environmental Services l Green Street Challenges and Design Considerations 51

52 Recommendations Step-Out Zones Identify the need early in the design process Use concrete step out zones Gravel step-out zones can be retrofitted to concrete Environmental Services l Green Street Challenges and Design Considerations 52

53 Recommendations Check Dams Right dam in the right place Concrete is the most durable and low maintenance Wood is best for swales and retrofit situations Look for long-lasting woods like Juniper Minimize gaps at the ends of wood dams Make sure dam height is correct Notches do not need to be in the middle Environmental Services l Green Street Challenges and Design Considerations 53

54 Recommendations Soils Need to look beyond infiltration rate alone for facility soil needs A good soil mix can benefit plant health and lower maintenance costs Environmental Services l Green Street Challenges and Design Considerations 54

55 Recommendations Rock Galleries Is the rock gallery needed? If a tree is required, can the rock gallery be removed, reoriented, or truncated to avoid interaction with tree roots? Can the rock gallery be designed such that plant roots can access the native subgrade? Environmental Services l Green Street Challenges and Design Considerations 55

56 Green Street Program Successes Green Street program began with three facilities in 2003 Grey and Green infrastructure work well together Overall, public acceptance of facilities has been positive Environmental Services l Green Street Challenges and Design Considerations 56

57 Questions Jeremy Person Environmental Services l Green Street Challenges and Design Considerations 57

58 Plants in SMFs Environmental Services l Green Street Challenges and Design Considerations 58

59 Plants in SMFs Challenges Plants must tolerate a range of conditions Slope, aspect, microclimate, upstream issues, heat island and sight lines (30 from top of curb) Safety and visibility Environmental Services l Green Street Challenges and Design Considerations 59

60 Plants in SMFs Considerations Plant selection helps control maintenance costs Specify plants that perform well for site conditions SWMM Plant List updated based on successes Environmental Services l Green Street Challenges and Design Considerations 60

61 Plants in SMFs Considerations Irrigation (postestablishment) is an ongoing cost FY12 - $32,000 FY13 - $53,000 FY14 -$50,000 FY15 - $70,000 FY16 - $73,000 Lined facilities 21% of our green street irrigation expense for 2015 (~$16K) went toward watering lined facilities (9% of inventory) Environmental Services l Green Street Challenges and Design Considerations 61

62 Plants in SMFs Considerations Visibility and pedestrian/motorist safety must be considered Environmental Services l Green Street Challenges and Design Considerations 62

63 Trees in SMFs Environmental Services l Green Street Challenges and Design Considerations 63

64 Trees in SMFs Challenges Trees, while beneficial, add additional costs to long-term facility management Choose the right tree for the right place Could be outside facility Environmental Services l Green Street Challenges and Design Considerations 64

65 Trees in SMFs Considerations Building new facilities around existing trees creates challenges Construction Added stress to tree BES responsibility for these trees Existing tree roots can disrupt water flow Environmental Services l Green Street Challenges and Design Considerations 65

66 Trees in SMFs Considerations Additional costs Pruning Seasonal leaf removal Extra irrigation Disease, damage, replacements Vandalism Environmental Services l Green Street Challenges and Design Considerations 66

67 Trees in SMFs Considerations Right tree, right place Consider existing canopy and trees Pedestrian walkways Growing space Uncertain future Environmental Services l Green Street Challenges and Design Considerations 67

68 Trees in SMFs Considerations Right tree, right place Visibility / Signage locations Environmental Services l Green Street Challenges and Design Considerations 68

69 Recommendations Plants in SMFs Plant selection helps control maintenance costs Irrigation may be required in LTM Site considerations are important to plant selection Right plant, right place Environmental Services l Green Street Challenges and Design Considerations 69

70 Recommendations Trees in SMFs Trees important to stormwater management Right tree, right place Criteria for planting a tree in a facility Can the tree be placed outside the facility? Environmental Services l Green Street Challenges and Design Considerations 70