Our First Drywell Design Under a Building

The blog has not been updated for a variety of reasons. One is that I went on a much needed vacation where I was told no working. I already need another one of those. I think some would be surprised just how many of these projects were being worked on while I was out of the country, either in a hotel room or while flying. But this biggest challenge since I got back was this redesign for a project in Glendale.

The original project was a 0.76 acre mixed use building a couple of blocks away from the Glendale Galleria and Americana at Brand. But as soon as those plans were approved and construction was under way a phase 2 popped up. We went to town to design phase 2 very fast and then we were hit with a huge roadblock. Phase 2 was going to be 0.655 acres and will now be considered as one large building. Even though the building don't actually touch, they sit 4" apart, we now needed to follow SUSMP instead of LID for stormwater mititgation. What does that mean? The City will no longer accept planter boxes as a stormwater mitigation to meet SUSMP requirements. Phase 1 drainage will change, while under construction, and Phase 2 drainage will have to change.

To make matters worse there was only one way to mitigate, and that was putting a drywell somewhere under the building structure, even though Phase 1's parking structure was being poured. The mechanical engineer came up with a great idea to get the drywell placed so it wouldn't interfere with construction. So why did the blog take a break? It turns out that not only did the City need both sites redesigned for the drywell but we also had to incorporate the plumbing plans into the grading plans, all levels from the upper deck to the underground parking structure. Oh yeah since construction was at the fastest pace this side of Dubai, we also needed the grading permits for Phase 2 yesterday.

Bringing the plumbing plans into our drawings was complex. Not only did we show the grading plans, survey, and updated Architectural siteplans, but now we are bringing in plumbing plans to the interior of a building. We do not normally show the interiors as grading plans have nothing to do with that. Also the pipe runs have to be more clearly marked out on our set of plans because we are showing the full pipe connections inside and outside of the building.

low impact development drywell

On top of that little plan oddity, we also had to design our first drywell that sat under a building structure. The Soils Engineer was extra cautious on their recommendations as now we are going to infiltrate the entire site into the building, through pipes and then into a drywell where a certain volume of water will be going into the ground.

From the section above we had to make it very clear what was going on. Where the water was coming in from, where the water is going, and if there is too much stormwater where does it overflow to. A lot of the new buildings under construction in Glendale have a system like this, but I bet very few building in LA designed something like this while part of the structure was already up. Literally two feet away from the proposed drywell on Phase 2, the Phase 1 parking structure wall was already in place. I just measured from the grading plans, to keep my sanity in check.

low impact development drywell

This picture gives a much better picture of what's going on. We had to show riser inverts for each level, the drain lines on each level, grades on each level, just everything related to water. And again its abnormal to show the interior of a building anywhere on the grading plans. In fact an old school engineer said you never do this and I have never seen it done. But here we are plans approved with construction to get underway next week.

If I was to take a guess I will never see anything like this for the rest of my career. Once again we took on something complex, got it done, and lived to tell the tale. It makes me feel good knowing this whole thing was approved in months, thanks to working very closely with the City Engineers. Just imagine what we have coming down the pipeline since we seem to have quite a few nearly impossible to build lots that we are designing. I think one of these lots is going to be our next blog post as we are going heavy into the design phase for three houses on a 1:1 cliff.

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