number and spacing of test pits. The Planning Commission therefore finds that the applicant <br />has provided the City with substantial evidence that the location of the test pits adequately <br />identify the geologic features of the site. <br />The applicant's May 14, 2019 Geotechnical Investigation identifies an area of previous slide <br />activity on the northeastern portion of the site as well as possible past landslide activity in the <br />southeast portion of the site. However, the applicant's experts did not observe any signs of <br />recent or active landslide activity. The applicant's May 14, 2019 Geotechnical Investigation <br />concludes that "[n]ew landslide activity is not expected, provided that primary landslide triggers <br />are mitigated during the site development. These triggers are: removing material from the <br />base of a slope or toe, adding surcharge loads to the top of a slope, and increasing water <br />infiltration into existing landslide mass." The applicant's May 14, 2019 Geotechnical <br />Investigation reiterates the recommendations in the applicant's February 6, 2017, Geotechnical <br />Investigation and includes the following additional recommendations: <br />1. Control the input of water onto slopes within the moderate and deep landslide <br />susceptibility zones and on existing deep landslides <br />2. Avoid adding material (weight) to the tops of susceptible slopes or, conversely <br />3. Avoid removing material from the bottoms of slopes (excavation or grading) <br />Based on the applicant's May 14, 2019 supplemental report and Public Works referral <br />comments dated July 29, 2019, the Planning Commission finds that the proposed development <br />will follow recommendation #1 (control the input of water onto slopes within the moderate <br />and deep landslide susceptibility zones and on existing deep landslide) by installing several <br />detention systems to restrict the peak flow rate of the post-development conditions to a rate <br />equal to or less than pre-development conditions (discussed further in Public Works Referral <br />comments dated February 28, 2018). Once the runoff from the impervious surfaces has been <br />detained via the detention systems, the runoff will be piped to a level spreader system located <br />near the east boundary line of the proposed PUD. While several opponents have raised <br />concerns related to this stormwater system, the Planning Commission finds that this proposal <br />(in conjunction with Conditions of Approval 17 and 18) will mimic the existing conditions on the <br />development site related to stormwater. The Planning Commission finds that a stormwater <br />system that mimics existing site conditions should not result in any additional geologic risk to <br />Final Order: Capital Hill PUD (PDT 17-1) Remand Page 7 <br />