Pathway Material Depths

Attached is a drawing describing the material depth of the 1:20 pedestrian roof pathway. The given spot dimensions are from the approx. top of slab to the top of decomposed granite surface.

Erosion blankets

These are photos of the erosion blankets that will be part of the installation and can be used to stablize growing media for planting at a later date.

Questions and clarifications

Good Morning!

A few questions and clarifications as we are on a fast train here:

1. CAD drawings:

How are the CAD drawings coming along to get to Charlie? He would really like to get started on the CD's ASAP as we have a commitment to Mark to get these to him and Martin by the 21st of December. If you can not provide them today when do expect to provide them?

I will work on getting these to you today.

2. Drainage:

We are still unclear how the drainage will work and concerned about the parapet walls being a very vulnerable point. Do you have comments on Charlie's comments? There seems to be two different ideas floating around one of many smaller ( weep holes/scuppers) that will be difficult to maintain and make sure they are not vulnerable to root penetration, or fewer larger scuppers that will be easier to seal and maintain. What are your thoughts and have you had a chance to look at all these areas of concern. We should determine and agree on a method ASAP.

Our structural engineer says he does not have a problem with larger scuppers as long as they do not interfere with the rebar spacing. We are looking to you for a direction otherwise. Whatever you recommend, we will send to the structural engineer again for a proper review and ok. (Also, FYI, with the rains yesterday we learned that the roof drains remarkably well.) I will review Charlie's email in a moment and respond.

3. Parapet walls:

The parapet wall installation is also of concern as again it is a vulnerability. Martin, what is the schedule and exact installation of date and method of these?

we know we now have the sacrificial layer on the roof deck. Will the walls be poured directly on this or would another layer of membrane be applied first and then the walls poured? We also think it may be a good idea to lay the root barrier down before pouring the walls to elevate most of the concerns. Have you thought of this idea or discussed with Epro?

The walls will already being poured over a polymer layer. Will two layers compromise the walls integrity?

We think it would help with the root penetration and vulnerability issue.

We should discuss this with WSA, Epro and our structural engineer.

4. Slope stabilization:

Anymore thoughts or feed back on suggestions in this area and the posted ideas? Do you want us to pursue an engineer for the anchor idea? I will need to clear with mark before we proceed. Personally i am in favor of the geo grid and think we have come up with some innovative and cost effective solutions that also allow us more flexibility..... any other thoughts? Charlie did you review the MST strap idea?

A recap of concerns:

1. How does the geogrid work to retain soil in this area and how can it be applied without inducing torsion and/or nonuniform loads as well as additional loads on the planter walls? How does the geogrid help retain soil on the south side of the beam- which is essentially a vertical wall?

2. The anchoring system seems to work and the structural engineer has approved this. This has the obvious concern of penetrations through the waterproofing which I think we would all agree is best avoided. I believe we have a typical detail for these kinds of penetrations from Epro, and hence may not be an issue. One note, the structural engineer has said he will not allow anchors in the beam- only on the slab.

5. Olive tree:

I would say max size 3' wide X 2.5-3' deep X 4' long is the area needed and it will be installed as a 24" X 24" X24" box .... we will need soil underneath and it will need to be pruned periodically.. i am awaiting maintenance care and will forward to you shortly. Max weight would be around 3500 lbs...

We are working with the structural engineer on making this work with a new footing design. He has requested that the tree be planted and kept in its box so that it does not induce forces on his retaining walls. Is this possible to do? Please advise.

Ok please let us know any questions, concerns or anything else you can think of.. we are all really working hard and need to work together now to get all of the specific details, get decisions made and get all of them recorded and drawn up so we can have a really successful project!!!!

Charlie's sleeving idea

If there is any question about how the slope will be supported, perhaps it would make sense to keep options open. When the medial walls are ‘shot,’ it would be a good idea to install 2” PVC sleeves through the walls every 2 feet. This way the a geogrid solution could always be introduced if the anchors end up being impractical or too costly.

Also, sleeves will be needed for electrical conduit and water supply piping.

The sleeves would not constitute ‘weep holes’ since we still have to be concerned about root-protection. See attached sketch.

Any further thoughts after receiving my preliminary flow pattern map for the green roof?

charlie's drainage comments

I am zeroing in on the drainage issue. See my attached diagram. This is how I currently understand drainage patterns after our recent discussions. Heavy red arrows represent concentrated flows. Lighter arrows distributed or sheet-like flow.

1- If in fact point B is at a higher elevation than point A, then we will need another scupper at point B. Please let me know what the slab elevations are at points A and B.

2- Scupper 5 and 6 will be points of flow concentration.

3- Significant concentration of flow is inevitable on both the north and south sides of wall ‘W’

4- Flow will concentrate along most medial walls.

5- Since there is only one drain north of the ramp, we will need another scupper at location 7.

6- After our conversation, I was no longer confident about the flow pattern near scupper 4. Will flow be toward the NW or SE along the beam (need to elevations along this obstruction)?

7- I think it makes more sense to manage water through one (or two) scuppers along wall ‘X;’ i.e., at A and/or B. The reason is that for water to follow the slope of the slab, it will have to flow through a number of additional scuppers and them be dispersed in a sheet drain under the decomposed granite pathway. I am concerned that this drainage path will be inefficient.

Please provide more information about what is happening where your plan shows a boundary between orange and blue. What is preventing flow from draining across this line? My understanding is that there are no drains along this axis.

I got the impression during our conversation today that you have been assuming that the medial walls will havemany scuppers; i.e., sufficient to prevent these walls from acting like barriers to flow. Do you have elevations of the walls, showing these openings? I am very concerned that root protection will compromised at scuppers. It will be challenging to hot-air weld the root-barrier so that it can protect the waterproofing in the opening. This is one reason that I have been assuming that the number of scuppers would be few, large, and strategically located.

Even if your plans are to have many scuppers through the medial walls, I still think it is important to have the ‘master’ scuppers in the locations that I have shown. These should all have vertical shafts that allow them to be inspected and serviced.

It would be great if you could provide a CAD file with spot elevations for the slab shown.

Since we are on a short fuse- please send current CAD plans and sections. We will use these as a basis for preparing details.

I will be available to discuss this some more on Sunday. Call my cell phone.

charlie's comments

Dear Carina and Lisa,

As I understand it the deck is being poured today. Therefore, any support system must either be designed without anchors or anchors must be drilled into the finished deck.

At the moment, I have the following pressing questions and comments:

1- The revised anchoring plan offered by the structural engineer is not, in any way, similar to our proposal. We have no objections to it, if this what the structural wants to propose. However, it is important to keep in mind that some of these anchors will ALSO have to be placed in the walls that will poured in the middle of the steep slope. This solution will require the ADDITION of a way to seal the root-barrier where the bar will penetrate through it on the downhill side of the wall. Off hand, I don’t have solution for this.

2- I will be happy to layout the anchors. The easiest thing will be to assume that there will be one anchor for every 8 sf. There will be about 300 anchors. The ONLY CAD drawing we have is A2.1.a last modified on 10-22-09. However, this drawings seems to be missing critical layers. Can you please send an Etransmit file for this, or a more recent drawing?.

3- Note that downslope from the raised beam, the anchors should be drilled into the beam. This beam should support the loads, and no additional anchors should be required downslope of the beam.

4- We are not designing the anchors. However, the final design must include a flange with a washer that will allow us to seal the root-barrier. The design could be as simple as a threaded bolt made from stainless steel or brass. The installation process would be to: 1) place a S.S. or brass washer 3” in diameter over the bolt, 2) force root-barrier membrane over the bolt, 3) a matching washer would be placed over the membrane, and 4) a S.S. or brass bold would be tightened over the upper washer. This concept design is simple to install and build. However, either the structural engineer of another engineer specializing in concrete must determine the diameter of the bold, its depth of embedment, method for securing the bolts into the concrete, and material (S.S. or brass). With this information Roofscapes, Inc. could research manufactures that offer bolts/washers that would satisfy the structural engineers requirements.

5- I have received no feedback on the drainage plan. In particular:

a. Will there be a line of roof drains following the northern wall of the ramp? Since the slab is being poured now, is the plan to go back afterward and bore holes for the drains. Are drains being cast into the slab now? If there are no drains along this alignment, this will definitely affect plans for drainage of the green roof.

b. I am confused about the pattern of flow in the small isolated triangular area south of the ramp (see area circled in pink on the attached scan). I would like to confirm that water will flow along the wall toward a scupper located at #5.

c. Do you have comments about the proposed locations of the scuppers

d. Will a large grate be added at the extreme southwest in order to receive flow concentrated flow in this area?

e. Are scuppers 4”x24” OK with everyone?

f. Once we know for sure where the grates, drains and scuppers are, we can layout the internal conduit that will collect concentrated flow and convey it to the outlets

g. Can you provide information on the design storm that is being used to size drainage facilities elsewhere on the site?

6- Where are the stub-ups for the irrigation supply? As mentioned in the past, these can be anywhere. We can run the piping below grade to where we need it. It is very important to include sleeves through the walls and curbs for the supply lines. These must be located before the walls are installed. Who is preparing this detail? Don’t forget electrical conduit.

7- With CD-time approaching, we should agree on a the details that will be generated by Roofscapes. We will need an up-to-date plan (see above) and all the sections. We can prepare dstials and specifications by 12-18. Details that we foresee as being necessary. Are:

a. Scupper (typ), including access shaft and distribution box

b. Perforated conduit layout

c. Perforated conduit detail

d. Slope stabilization assembly

e. Assembly profile for shallow soil areas, including typ. detail for capillary irrigation system.

f. Assembly profile for deep soil areas

g. Area drain detail, showing access chamber

h. Transition to decomposed granite walkway

i. Transition to wall

j. Detail at slope anchor

8- Irrigation design is not in our scope, but we can provide basic information in the specification that will guide the installation. We can also provide you with some ‘boiler-plate’ details for valve chambers that you can add to the CD set. You can ask for the irrigation layout, based on Netafim, to be prepared by the contractor and submitted for approval by Belsberg.

9- We will provide specifications for the various green roof profiles. It would make sense to include the decomposed concrete pathways in the green roof specification, since drainage underneath the paths is integrally related to the adjacent green roof areas.

MST Strap

Carina,

I’ve attached some data you can forward to the engineer that the landscape architect is going to use to design the soil retention system.

This is a metal strap that can be fed beneath the planter wall at Grid ‘D’ and allow us to bolt to the flat portion of roof while still leaving about 36” of strap at the downhill side. This should prevent loads from transferring to the wall because it’s not using the soil on the flat to hold the geo-grid.

- just an idea you can maybe work from; William Koh seemed receptive to the concept (I already spoke with him about it)… but you do still need to provide him with engineering for the entire package so he can review it against the loads his roof is designed for.

Eric Steppner

charlie's new idea

anchor issue

charlie's estimate, based on a FS of 1.25 is as follows

45 degree slope

Horizontal spacing

2 4

Vertical

Spacing 2 250 lb 504 lb 10 rows

4 504 lb 1,008 lb 5 rows

6 756 lb 3 rows

33 degree slope

Horizontal spacing

2 4

Vertical

Spacing 2 179 lb 360 lb 10 rows

4 360 lb 720 lb 5 rows

6 540 lb 3 rows

thermal value, anchoring and drainage

With regard to Carina’s comment; I assume that the R of .25 is an accepted average for soil. I think that the number is about right, on average. Of course R varies tremendously with moisture content and is not a stable number with soil. It will be nil after a soaking rain. However, the effects of thermal capacitance and latent heat transfers produce effects that behave a lot like insulation under specific circumstances.

I am attaching some scans of marked up plans (based on 10-22-09 revision). As soon as possible we would like to receive current CADD drawings that pertain to the roof (plans, details and sections). We will build our details and sections off of these.

Scan #1- First option for lines of anchors. The purple line represents the south side of the exposed beam. The red lines represent attachment to the medial walls. I understand from our conversation that attachments to the walls may not be necessary. However, I am showing the option nonetheless.

Scan #2- Second option for lines of anchors. In this case the anchors would be set into the slab. As we discussed, none of us like all these penetrations through the waterproofing. However, if this is the only option, then we will have to rely on Dave Polk to come up with a reliable way to seal them. It seems to me that these would have to be stainless steel if they are set in the slab. However, the group may have another idea.

In both of the above cases, I recommend that the anchors be 18 inches apart (east to west alignment). Cables will be attached to the anchors which will either support a cellular confinement web or a high-strength geogrid. With 12 inches of wet soil on a 20 foot long slope with pitch of 1:1, I estimate the force on each anchor as being about 1,800 pounds , with a factor of safety of 1.5. However, most of the slope lengths will be shorter, averaging 10 feet, and ranging down to zero. The force on an anchor supporting a 10 foot long slope would be about 1,200 pounds. It would be simpler to have all anchors the same, but it may be cheaper to tailor the anchor to the load requirement.

[there is another interesting possibility. A high strength geogrid could be laid out on top of the completed waterproofed slab. Each strip of geogrid would extend from the northern-most wall all the way to the bottom of the slope (I think about 50 feet). The medial walls could be poured on top of the geogrid. Now… you can see that each MD stand of the geogrid would be weighted on the flat surface by the overburden. I haven’t done the math, but I think that this stabilizing/resisting force would be sufficient to support the downhill forces on the slope. No anchors needed. This could be a simple and inexpensive idea if the architect and engineer don’t think I am crazy.]

Scan #3- shows areas where there will be no sheet drain

Scan #4- my PRELIMINARY assessment for where scuppers will be required. I am assuming that there will be a row of area roof drains, as shown on my mark-up, and the channel drain --- nothing more. The scuppers which are shown as red boxes would be essential. There are six. It would be a good idea to increase the number of scuppers. The orange circles represent tentative locations for supplemental scuppers. The scuppers represent the only places where flow can pass across a medial wall. The arrangement of scuppers, as I have shown them, would avoid one of the conditions we briefly discussed today—namely runon from uphill areas into the area subtended by the lower path. Rather water would flow through scuppers 5 and 6 and then along inside the narrow planter all the way to the southwest corner. I do not think that the channel drain will be sufficient to serve this flow. An area drain should be located immediately downgradient of scupper #1.

Note that there will be a very large rate of flow generated by water accumulating against the medial wall that I have labeled ‘W.’ This flow will be ‘piling’ up under the path. Therefore a sheet drain (e.g., eco-drain-S 900) will not be sufficient to convey this flow to the west. Perforated conduits must be installed under the pavement to carry this flow. To allow enough ‘head-room’ for this conduit, the thickness of the path profile may have to be greater--- perhaps 8 inches, instead of the minimum of 5.5 inches we discussed earlier.

Note also that there is a great concentration of flow at a single point which happens to be at the same place that scupper 1 outlets. I am certain that a large grate, not a channel drain will be needed hear. Alternatively, area drains could be installed to cut down the volume of flow.

I don’t understand the pattern of flow in the area circled in pink. Earlier plans showed the flow direction north toward drains on the south side of the ramp. I don’ t think that these exist anymore.

What is the design storm that is being used to size runoff conveyances elsewhere on the project?

In the absence of a designated storm, I think a good starting point would be to think of each scupper as 4 inches high and 24 inches wide. The inverts would be the surface of the slab. At each of the six primary scuppers a vertical shaft would provided to allow inspection (and cleaning if necessary). The shaft would have a lockable lid.

Scan #5- This is rough hand sketch of conditions at the section labeled alpha on the plan.

I assume that these sketches will spur some more discussion. Next step will be prepare proper construction details for the various conditions, using the architectural CADDs as a base.

Roof Drainage-As Built

revised soil depths/plant height

Aaron,

Lisa will go over this with you along with questions/concerns we have.

RE: Charlie's comments

4. Barriers to flow: Many of the walls, unless modified, will provide barriers to water drainage. There are two possibilities: a) install these walls over high-strength sheet drains that will allow free flow of water under the length of these walls, or b) provide substantial scupper openings at all low points. We recommend building rectangular scuppers into the walls, each several inches high and a foot, or more, in length. We can work with the design team to determine how best to design and position scuppers.

Refer to detail attached (from #3). We had planned on providing weep holes at the bottoms of walls to allow drainage of water. // See comments above—we recommend large rectangular scuppers or, alternatively, casting the walls on top of sheet drain. Please provide a drawing showing the size and locations of weep holes so that we can submit these to our structural engineer. Please note that the engineer has already given us a max penetration through beams (of which we have a few we will need to drain through) of 2" diameter. // beams are a special case, since these must be cast in the initial pour and they are structural. You mentioned that circular penetrations are not as effective as rectangular. Please confirm your preference. // We definitely want rectangular openings. If a 2” clearance is dictated by the engineers, then we would suggest a series of 2”x8” or 2”x6” sleeves be placed through the beams before the pour (we suggest Certainteed Form-A-Drain for this purpose). Can you confirm this with your engineers? Also, we need to think about installing 2” diameter pipe sleeves through the beams (and walls) for electrical and irrigation lines. A preliminary layout for plumbing stub-ups, irrigation supply lines, and electrical conduit should be prepared before the slab and beams are cast. William Koh the structural engineer will need to know the the worst case scenario of the spacing between weep hole locations along the planter walls.

Plan 03-Beam Clarification

Please see the revised roof plan. Notice added item 14.

Clarifications

In regards to our conversation today, I wanted to clarify a couple of the things we discussed.

A) Because the plant palette is not yet finalized, the green roof profile is not yet finalized, however, the roofer only needs to install the waterproofing membrane. All other components can be considered part of the green roof profile and installed by the green roof installer. This will help to insure that the scope of the green roof is not broken up and accountability is easy to assess.
-No sheet drain needs to be provided by the roofer or membrane manufacturer (although it may be part of the green roof system depending on the ultimate build up.)
NEED CLARIFICATION-Roofscapes, Inc. is unclear if insulation is required in the build-up. We have discussed using insulation to meet elevation requirements but we are unclear as to whether it is otherwise required in the roofing build-up. Please clarify.

B) Roofscapes, Inc. provides a warranty for our green roofs, however this warranty is only offered if the green roof (all components above the waterproofing membrane) is installed by a trained and licensed Roofscapes, Inc, Network Contractor (much in the same way that roofers are certified to install particular membranes). Roofscapes, Inc. will be on site to supervise the installation as part of our Quality Assurance Program (see attached). If there is a contractor that is not in our Network, we would be happy to discuss the option of them joining our Network.

C) 3 membranes are being considered, EPro, Sarnafil, and American Hydrotech.
-The EPro and American Hydrotech products require an extra root barrier to be installed over the membrane. Please make it clear if the roofers intend to install this layer, what exactly the product is and how it will be installed. Roofscapes, Inc. recommends a minimum 30 mil polyethylene, polypropylene, or PVC, heat welded at the seams.
-The root barrier could be installed by either the green roof contractor or the roofer.
-EPro and American Hydrotech should confirm that they will honor their waterproofing warranties with the designed green roof on top of their membrane. Sarnafil and Roofcapes, Inc. have a national agreement to provide a comprehensive warranty covering the entire system including all components above the waterproofing.

D) EFVM testing is a leak detection method.
-The test can be used as a quality assurance measure (preceding green roof installation) to insure that the waterproofing is water tight and it can also be used to locate a leak if one occurs in the future.
-In order to use the test for quality assurance, nothing needs to be installed under any of the membranes as long as the membrane is in contact with the roof deck. If Sarnafil chooses to install their system over other components then a grounding screen should be installed directly below the membrane in order to use EFVM for quality control.
-When the test is conducted the technician will place a wire around the perimeter of the roof areas. Laying this wire is part of the cost of the test and does not need to be included in any contractor's scope.
-The root barriers that will be installed with the EPro and American Hydrotech systems could potentially interfere with the use of EFVM should it need to be used to locate a leak in the future.

E) The concrete walls WILL NOT be poured on top of a sheet drain, which means that rectangular scuppers will need to be installed in the walls in order to facilitate proper drainage between the different green roof areas.
NEED CLARIFICATION-Roofscapes, Inc. has not seen a roof plan that shows where the roof drains are actually placed on the roof. Please send us a plan or photos that show where these drains are actually located so that we can create a plan for where the scuppers need to be placed and how large they need to be.

F) Lisa and Karla are getting closer to finalizing the plant list. Once the plant list is understood we need to clarify exactly what the water burden will be for the irrigation system.

Please let me know if you have any questions.

Regards,

Nate Johnson

EPRO drainboard etc.

Martin is meeting with Roofscape's rep or installer now as I write this entry. I have to clarify Charlie's communication which I told Martin...

On 10/30/09 I Charlie Miller spoke with David Polk at EPRO

His notes indicate:

1- They use a 15 mil root-barrier membrane. I asked for the root-barrier to be overlapped by 4 feet or hot-air welded. David agreed to this requirement.
2- EPRO has a drainage sheet product. They would like to use it (of course), but David said that they would not be dogmatic about.
3- I told David that Roofscapes, Inc. would allow EPRO to review and approve our green roof design.


For the record, Martin's number is 310-473-8490 at the office and 310-948-2730 for his cel.

charlie's comments

Our comments are as follows:

1. Slope stabilization: With the wall layout, the only viable approach to support the steep slopes would appear to be by suspending cellular confinement webs or high-strength geogrid from the top of the slopes. Since the pitched areas are transected by walls, this will mean that attachments will be required along at least 5 different wall segments and also at the structural bean on the far west of the project. These attachments could take the form of stainless steel anchors that are either cast into the walls or installed by drilling into the finished walls. In our opinion, the spacing between anchors should not be more than 18”. Once the thickness of the soil layers in planted zones 3, 4, and 5 are established, Roofscapes, Inc. can compute the static pull-out forces for the anchors. The height of the anchors above the slab will depend on the final design for the landscape. Moment forces associated with these anchors will have to be taken into account for the design of the walls.

This sounds like a good approach. Please provide drawings and specification that we can send to our structural engineer for review. //The first step is to determine the profile for the planted areas. This will establish the elevations for the bottom of the soil profiles.

2. Border edging: In transitions between decomposed granite and planted areas (associated with planted zones 1 and 10, some sort of structural edge will be needed to stabilize the decomposed granite walkways. While this could be custom fabricated stainless steel, we believe it would be considerably cheaper to cast curbs at these locations (green lines on the layout).

The planted zones you refer to are defined by planter walls, so those should not be an issue. // the planted areas that are inboard of the walls and adjacent to the walkways do not currently show walls or curbs (areas 1 and 10 on my attached diagram). However, your point does apply to defining zones 11,12, and 4 (in some areas) from the walkways. We were thinking if the material can be kept below grade so that it is a not visable, would a plastic fence be more cost affective.// If the edges will be invisible (below grade), either a plastic or aluminum edge can be used. These must be installed in conjunction with a reinforcing mesh to provide horizontal stability. Also, we assume that the decomposed granite walkways will be installed over a high strength sheet drain. The edge detail must promote flow under the edge and into the sheet drain. This is one of the details that we will prepare. Note: These edges could also be cast-in-place concrete.

3. Walkway transition: We would like to receive a definitive cross-section showing the transition between the decomposed walkway the planted zone 10. We believe that the most practical solution for this transition will be to install the decomposed granite (and curb) over a high-strength sheet drain. This will allow percolated rainfall and excess irrigation water to flow underneath the walkways. Effective uniform drainage of the planted zones is essential. Alternatively --- the walkways could be constructed as barriers to flow. In this case an efficient subsurface drainage network will be required to collect underflow and convey it to an area drain located within zone 10.

See detail attached. We have a drain board specified for the entire roof (1" ) and up the planter walls (3/8"). // As stated above, we presume that a 3/8” thick strength sheet drain will be installed UNDER the walkways. The transition of flow at walls will be tricky and will probably have to be handled in various ways. One solution at walls will be to install a 1” sheet drain UNDER segments of the walls before they are poured/shot. This is a simple, effective, and tested. However, as we have discussed, at some locations rectangular inserts may be placed through the walls, creating high-efficiency ‘scuppers.’ Transitioning runoff to the subsurface scuppers will take some design planning. Roofscapes, Inc. has agreed to develop proposals for these various drainage conditions. Note: We see no reason to place sheet drains up the face of walls.

4. Barriers to flow: Many of the walls, unless modified, will provide barriers to water drainage. There are two possibilities: a) install these walls over high-strength sheet drains that will allow free flow of water under the length of these walls, or b) provide substantial scupper openings at all low points. We recommend building rectangular scuppers into the walls, each several inches high and a foot, or more, in length. We can work with the design team to determine how best to design and position scuppers.

Refer to detail attached (from #3). We had planned on providing weep holes at the bottoms of walls to allow drainage of water. // See comments above—we recommend large rectangular scuppers or, alternatively, casting the walls on top of sheet drain. Please provide a drawing showing the size and locations of weep holes so that we can submit these to our structural engineer. Please note that the engineer has already given us a max penetration through beams (of which we have a few we will need to drain through) of 2" diameter. // beams are a special case, since these must be cast in the initial pour and they are structural. You mentioned that circular penetrations are not as effective as rectangular. Please confirm your preference. // We definitely want rectangular openings. If a 2” clearance is dictated by the engineers, then we would suggest a series of 2”x8” or 2”x6” sleeves be placed through the beams before the pour (we suggest Certainteed Form-A-Drain for this purpose). Can you confirm this with your engineers? Also, we need to think about installing 2” diameter pipe sleeves through the beams (and walls) for electrical and irrigation lines. A preliminary layout for plumbing stub-ups, irrigation supply lines, and electrical conduit should be prepared before the slab and beams are cast.

5. Flow patterns: Based on Drawing A2.1e and P-2, it appears like the rows of drains located on the north and south perimeters of the building as well as the row immediately south of the ramp will serve only the narrow planters in these areas. In particular it appears like the southern row cannot be effective in capturing runoff from the adjacent and up-gradient planted areas and walkways. Is there a plan to connect the areas north of the high parapet wall with these drains? We can be of assistance in suggesting some solutions.

I believe the row of perf pipe on the north is no longer necessary and is an artifact from an older design. The intention of the southern row, at the perimeter of the building, was to help carry water in that narrow planter towards the west. Please advise if you believe this to be true. I am not sure that the row south of the pedestrian ramp helps either; please advise. //Where will the roof drains and channel drains be located. Is this flexible? The drainage plan will be based delivering water efficiently to the roof drains. Who is in the lead on this?

6. Waterproofing flashings: We understand that most, or all, of the walls will be constructed using shot-crete. Will this concrete be hydrophobic? We are concerned that if this concrete can absorb water, it will become necessary to flash the walls at least 6 inches above the soil layer. This will have aesthetic and cost implications. There are many possible solutions for flashing the walls. We would be happy to discuss these with the team.

Our shotcrete walls are all 5000 psi concrete. Given that and the attached waterproofing detail, the flashing is a secondary measure. Will we have plantings that can cover the flashing if it is 6" above the soil? Can this be reduced at all? Please advise. // I do not have sufficient information to conclude how the waterproofing flashing should be installed. If the waterproofing contractor will certify the deck as watertight, even at re-bar dowels, then wall flashings would appear to be completely unnecessary. What sort of guaranty is the waterproofing installer providing? The nightmare scenario, if there is one, would appear to be moisture absorbed into the shotcrete walls, migrating to the rebar dowels, rusting the dowels and compromising the waterproof slab. I have no idea what design precautions have been made to mitigate against this possibility. We know of other jobs (Sika Sarnafl) where walls cast on top of waterproofing required no wall flashings. If there is any uncertainty about this, then I recommend that the flashing be extended up the wall and 6 inches higher than the top of soil.

7. Irrigation: Unless 2” diameter sleeves are installed across and under the various walls, curbs, and walkways, stub-ups for irrigation will be needed in every planted zone. Also, the irrigation valves and controls can be either centralized inside the building (e.g., in a closet or utility space) or they can be placed on the roof. The downside of placing them on the roof will be that each irrigation zone will require its own valve chamber (typically 8”-12” high, 15” wide and 24” long. These will be visible.

2" diameter sleeves are being provided under the planter walls and walkways. Irrigation valves and controls will not be inside the building but in the planter areas. How many zones do you calculate we will need? My understanding is that these boxes will be flush with grade- lets work together to be strategic about where these are placed so that they are not in highly visible locations. // The boxes can go anywhere. The number of zones will depend on the planting plan, and the desire (if any) for flexibility in changing the plantings in the future.