intersection had for gas stations? now you cannot find a gas station anywhere? those four gas stations had leaky tanks. now we also have to look at the presence of hydrocarbons in the soil. >> moving along, the perfect setup for the next question. >> when we went out on our long walk together, we talked about the relationship between the nature of a building, primarily its height, and the soil on which it sits. the slide is a good reminder of that. >> the ground has a natural period. the denser the material, the harder the material, the shorter the period of the ground. bay mud, which is present close to the shoreline, and the green

area, the crown has a very long period. when the earthquake comes, there is a link of time that it takes the ground to go from one, slosh back and forth, measured in seconds. the deeper the bay mud deposits, the greater the length of time it takes for the motion to go one direction and back. so as you approach soft sites, loose sand sites, bay mud sites, the period of the site is long. if you come along and build a tall building, and the ground is going like this, we know that tall buildings, the taller the building, the longer the period, the longer the time it takes to go from one side and back. iand the rule of thumb, every story that you add, it adds a

10th of a second to the period. if you have a 40 story building, you have a building that takes four seconds to go from one side to the other and back. now, that for second building is sitting on 100 feet of bay mud that also has a period of four seconds. the combination of those and harmony, what happens is they amplify the motion and the building will collapse. example, the infamous bridge. in that case, the wind got in harmony with itself and it collapsed. what you try to do is you try to put a building on a site so that if the ground it is a long period, you want the building to be short. if the ground is short period,

you want the building to be long. that is what happens when you get into the financial district. quite often, they will go down through the bay mud, put the structure on dense sand that has a very short period, and building is at 40 stories high with a very long period. even though the ground is doing this, the building is slowly moving. so there is damage, but there is less risk of damage. alternatively would have done is layers and we've springs and all kinds of different -- and leaf springs and all kinds of different tools that can take the structure and put them on face. -- on phase. so when you look at a building like this, 10 stories, the period of that is about one second, 1.5 seconds. that is probably sitting on that sand or rock and that is about a quarter cent.

so it is ideal. the ground is going like this, the building does not feel it. you feel it, but the building, it is not doing damage to the structure. >> the building next to it, let's say it is wood frame. what are thoseeperiods? >> there are less than a second. the beauty of a wood frame building, it is probably the most forgiving construction. it squeaks, the plaster will crack, and if you don't have the soft story to deal with, you just have your cup of coffee and the one with your life. >> i guess this is turtle bill. >> grandview, turtle hill, san the mountain, -- sand mound, depending on how long you have been living there. >> this is northwest, of golden gate park. the nearest background, sunset and the richmond district? >> way out to the end, that is

for smiley, the veterans hospital. this is for smiley. rock, rock, rock, rock, rock. here is hunters point. that rock is called serpent tonight. -- serpentinite. along this zone, there is another rock type, volcanic rock. it is serpentinite. it is a very treacherous rock. if you go up market, you will see it where the met -- barack is exposed in that cut. -- for rock that is exposed in that it is cut. it can be hard work and have the consistency of soap and just slides. why is it like that? it is an intrusion. it is like toothpaste that was

extruded through a crack in the earth. that means it was a sheer zone or fault, hundreds of millions of years ago, where it actually came up through and bubbled out and formed this band of serpentinite. adjacent to that is this wonderful rock. what is the other thin that is bad about serpentineite? it contains naturally occurring asbestos, which is a carcinogen, known carcinogen. if you go to where st. mary's cathedral is, cathedral hill, that is one of the outcrops. there is a high percentage of serpentinite in the rock. in the old days, the 1930's, 1920's, san franciscans to not bother to deal with the disposal companies.

they would take their garbage out the other side of twin peaks, bump their garbage, and shovel sand on top of it. so in the old days, you could go out there and build your home and be surprised that you would find sanitary landfill or construction debris landfills. they were prevalent out there. >> this is twin peaks? >> going up to twin peaks. >> one form does not change much. >> eucalyptus trees have got much taller. that is not halt leading up to predict that is the hill leading up to there. fifth avenue, that area of san francisco. ucsf. that is this area right here.

>> it is an earthquake hazard micro zone. >> again, another example of the wpa. the streets, they wanted to get to the top of the hill, said the duties beautiful walls and stairways. they are doing well. >> all of these hillsides have catalyzed the design and construction of the interesting foundations and sub framing. >> up there, you'll find quite often, because it is rock, they have dug holes, filled it with concrete, put pulls up, and built their buildings. they have been there actually now 67 years. >> some of these are significant earthquake hazard? >> many of them, because they're not properly braced, because the foundations are not deep enough. the consequences could be significant during an earthquake. >> the tunnel opened that whole

section up to development. did that lead to park side? >> west portal is right here. it this slope. westport open up this whole area down here, with the reservoir. the tunnel was built and two different ways. one of them was cut and cover, the other was a tunneling machine. as they came close to the side of the hill, they dug down vertically, took out the dirt. they took the dart -- they took the dirt and replaced it as phil -- fill all along the lower part of market street. they filled in the ravine. >> thank you all very much. that was a heck of a tort of san francisco. thank you for your attendance. we hope to see you every third thursday right here.

thank you for coming. this is the department of building inspection brown bag lunch series at the department of building inspection. i am the chief inspectionor and we're looking at a interesting topic today which is commercial signs in san francisco. everybody has a point of view. some people love them. some hate them. they have a meaning and an important part to play, so it will be a fun tour, and i have

signs to show you and use as a base of discussion and westbou e your questions. we have two quests introduce. jeanine pab pabilsky and she's an artist and a cultural historian and the founder of "bureau of urban secrets". >> it was found #- founded in 2g the dot com boom and engage artists and helping us interpret the city and we have done about 25 art projects in the city, and the most recent project is still on going and historically

document the experience of the statutes of jaun bastila and king carter of the third and founding of san francisco and then homeless and upcoming we have a project of landsend. >> artistic intervention. i love that phrase and we have scott sanchez from the planning department who is heavily involved in the sign issues. what are you working on now scott? >> we are launching the sign inventory so it's going to be an inventory of the advertising signs in the city and county of san francisco. we are getting inventories of sign companies and doing surveys. >> i understand that we are doing a city wide historical building inventory. are they

linked together? >> no just for preservation and we will work together where we can. >> while you are out there i need some stuff i need to know. seriously once we are around looking stuff and we can populate the data base with other good information. that's great. we're glad to hav to yo we have a couple folks also here from sign america. thank you very much and i invited them to talk about the sign process. we have a lot of people here that know about signs. signs are such a big issue here in san francisco. i divided up the pictures and topics into four basic parts of the first is signs that advertise the commercial property for which they are located and here are the 500 club of the i think it's

at 17th and valencia and somewhere in the planning department said and visible signs of represent and one of the things we really want to see and some people don't agree. i can share my point of view and you as well. another sien sign we're going tk at are the general advertising signs and corner of mission and 17th and r replace the other sign that was up there and hopefully an issue in the city and hopefully we can talk a

little bit about that. another type of sign that you see are historic signs and signs that are both on buildings and in some cases those historic businesses are still in operation. do we still have abbert flap jacks around? me neither. and the fourth category is all the other stuff going on in the city and how are they regulated and what -- do we like them? is it a good thing? this is down in the mission and these folks are actually on a mural walk using a guide through the mission so let's start with the mateeny class. you can never have too many martinis? >> it adds to the day.

>> okay. good. this is on the 24th -- i think bryant. the building code says when you build something with a permit and you're able to keep it unless the code retro activity changes. how old do you think it is? >> (inaudible). >> 50 years old. there is nothing retro actively that says that have you to remove a sign. is that correct? >> 24r was a case on there was a case on market street and we did it for signs and a couple had to be removed but generally no. once it's non conforming could remain until the end of the life of the sign. >> so generally that is the case

with all building issues is that are you permitted to retain those that were properly installed with a permit unless there is specific legislation that says otherwise typically. is this a flag sign? is that what they call signs that stick out like that? >> projection signs. >> projecting -- projection signs and it's painted and neon and the required martini glass and you can see it's stabilized by wires to keep it from falling and the wind from pushing it side ways. the signs are regulated in the building and planning code and requires it for all signs and we will talk about what "all signs" means and does it include the sign that says "special summer sale" and the building code and the planning code goes into great detail of the requirements for

signs. >> square footage and whether projecting on an awing. >> okay. this is market and valeensia and this is the sign and you can't have too many neon because i understand that you're allowed to have a sign on either face of a corner building. is that right? >> depends if you're going to have a business sign and the business is on one side of the building and could extend but not on that side unless the business was -- >> in this case they have a sign on this side and on the backside and then a flat area facing directly across to market street which is a third sign and with an interpretive issue whether they're allowed to have a sign on that, and that's where we said you can't have too many martini glass -- not a glass

but a beautiful fish sign -- where is it? seventeenth in the portero area and here is one of the corners we're looking at, and what is interesting about this slide to me, and maybe you can share thoughts. it does not have the gigantic sign and there is no sign "this is the something kava". >> this is one of the exceptio exceptions. >> and this is interesting and you can't have too many martini signs in the city but there are neighbors that would say you could have too many bars and there is a sense of changing w e way people use the city and you look at the martini signs and imagine people kicking back with a drink at the neighborhood bar and a place that you felt at home and maybe you conducted

business if you had that kinds of business to connect, and in a way in the city and a lot of that -- even though we like to drink has been replaced by the cafe and it has a different look and no one would say at this point that you couldn't have enough starbucks in the city and that as a meeting place has replaced the bar and how do they present themselves and how do we understand that starbucks may seem says intrusive but 50 years from now we will yearn for that and got the prozac at the corner dispenser rather than the cafe or the martini bar and how do the signs become a memory? >> and another old corner with a similar kind of design where it

has the small window lines among the glazing and the reason they built these and the plate glass windows and typically have an awing and the window above would light it and the awnings would shade the produce and other things and if you're walking by there watch out she's about to throw the water into the gutter. >> is that a violation? >> she should clean the sidewalk. >> that is interesting too. there is a lot of discussion and you guys probably know more about this than me and the larger ceiling heights and more retail space and allows for the delightful space for sign space as well and the old lip ton tea

signs are a memory of what the corner retail spaces could be like. >> right. these are separate signs that we have on the judda street, golden bear market is one side and painted on to the windows. are they considered signs by the planning department? >> they have the business sign and the amount of street footage dedicated to that and the square footage of all the signs together so we would calculate -- basically draw a box around the letter and the square footage. we don't regulate the content of the signs and general advertising signs, and when it comes to us a lot of them put it up like that. >> are the miller litte and

corona signs in your view? >> they are allowed 1/3 or 25 square feet and advertising on the business sign and wheneve wr and can contain the seven up on there. >> is there a difference between an awing that is used with lettering on it and a general advertising sign for a specific business location? >> we consider general advertising sign the advertisement of a good, service that is not available on the premises or is only -- you know, more of incidental presence on the premise, so we consider anything general advertising meeting that definition. >> with a particular business with an awing lettering or identifying signs on the awing is calculated into the same calculation as determine whether

they are using their allowable advertising for that location? >> right. for the business sign. when you can have the sign on the awing and that is based on the square footage. >> and one more awning question and i know they have talked about new guidelines in businesses in our district. do you know whether or not that is possible for the corner stores? >> we are working on a survey of downtown to develop sign guidelines for the downtown district. i'm not aware for that district. >> you mentioned that you don't regulate the content of general advertising signs. i am wondering what is there threshold of language and somebody say this language offensive, substandard. >> no. issues have been raised

with various clothing stores but in terms of actual regulation we don't regulate the content. >> obviously lines of profanity. >> it then might go to a police issue but we wouldn't regulate it. >> about the sign and the aliens and big brouhaha and the board of supervisors took it up. >> i don't have information on that. >> yeah. i think part of it - >> down by the market street and i will pass it around and you can see that the office is totally covered with signs so this -- signs are not a new

thing and there are more signs here than we have today and we don't have as many on the downtown buildings. >> i think part of that is in 1913 a city ofs a place of culture, commerce, and industry and the signs in a literal and metaphorical way were present in the city but we're debating now what cities are and sustainabl sustainablity and environmentalism and once you say that maybe signs are not a part of the city or unnatural or don't speak to the values of a non consumer oriented culture and make clear for example. i think this kind of notion and the notion of signs and beautification is also an issue. >> this picture shows both the

general advertising. this used to be the buy it yourself casket company. you could beretail caskets. what a loss to the city. it says on the window for lease and there is a provision in the planning code when a business is gone the sign has to be removed within a certain lent olength oftime. do you know th? >> no not off hand and the business sign goes with the business and once it's gone not considered a business sign. >> and it's in the code and it says how long you have and i think 90 days and the business code says that as well. here is

another one of the corner signs and it's interesting it's not a modern starbucks kind of institutional sign but independent individual sign and a great restaurant too by the way. here we go. we're in another district here. we have hand painted signs and in some ways around the city you see these signs and made by people rather than contacted out to the sign paren paint are but it coue the sign painter. do these count as part of it? >> generally they're painted on the window like that and you can have them in the city and the temporary signs and painted on. >> fascinating. on 24th street a new